Miss Finster has a raspy voice because she smokes, or used to.
Spinelli's size changes as the series goes on. She's the shortest at times, but at the end of the series she's TJ's height. This is due to a growth spurt.
A lot of one time characters disappear without an explanation while some leave at the end of an episode. It's possible Gelman the Bully scared them away, like he did to the kid at the beginning of "Gus' Last Stand."
Ashley, Tyler, and Britney/Brittany are all very common names; it would make sense that there would be more than one in the school. The Parents' Night episode implies that the Ashleys' mothers are all friends so it could make sense they'd all give their kids the same names.
In "Speedy We Hardly Knew Ye", Miss Grotke knows full well that Speedy has died and is trying to use the 'meditation' excuse to buy some time for her to replace Speedy with a new hamster.
There's a background character named Phil (he's the one in the scout uniform, red curly hair, buckteeth) who is in a few episodes. He's part of the Woodchuck Scouts, which is meaningful for his character design considering he has buckteeth.
In the episode "The Challenge" at 98th Street Elementary (where Prickly's brother's the principal) he meet the gang's doppelgangers at the school. In the episode after it, "Dance Lessons," Spinelli does ballet and meets some doppelgangers of the Ashleys named the Megans. Even though we don't see them in the previous episode, it's safe to assume they attend 98th Street.
Miss Finster's heart-to-heart with Spinelli in "That Sinking Feeling" comes after the events of "The Trial" and "Weekend at Muriel's." Finster remembers Spinelli helping her cat out of the tree and the fun weekend they shared when Spinelli stayed at her apartment, so she wants to make her feel better when she sees her looking depressed.
The entire school changing their names to Ashley in "First Name Ashley". Ashley Q protests "you're not even girls!" - Ashley is a boy's name in the UK, and (while uncommon) in the US too.
Hypnosis cannot force people to do things against their will. Thus in the episode "The Hypnotist", when Principal Prickly is hypnotized into thinking he's a six-year-old, it reveals a subconscious desire to be a kid again.
"The Library Kid" has this gem from Gretchen: "Drive her into the existentialists! There's No Exit!"
In one episode where Gus was designated King Bob's substitute, his first act as king involved him settling a conflict that he solved by floundering through and ultimately botching a Judgment of Solomon, this perfectly foreshadowed his brief reign becoming tyrannical and ultimately self destructive.
In "The Shiner", King Bob lavished T.J. with praise for supposedly quelling a Kindergarden uprising. In a previous episode, "To Finster With Love", just such an uprising temporarily drove him off of his throne.
Mikey's huge size and Big Eater tendencies aren't just a funny contrast to his gentle, sensitive personality, but actually fit with it. First of all, highly sensitive people are often prone to emotional eating and weight problems. Secondly, it makes sense that a poetic personality like his should relish all sensual pleasures, including food.
In Recess: School's Out, the film ends with one of Dr. Benedict's lackeys offering to turn state's evidence for the trial; Randall, overhearing this, remarks "Geez, what a squealer!" This might look like a simple case of Hypocritical Humor, but the series reveals that for all of his love of snitching and tattling, Randall is completely devoted to Miss Finster, and would never think of betraying her. That's why he's so disgusted with the idea of Benedict's minion ratting him out—he can't even imagine doing the same to Muriel.
Hank knowing advanced math seems like a Throw It In! gag done for the sake of an Almighty Janitor joke but it's revealed that Third Street Elementary is heated by a boiler. Boilers require special licensing as well as training to operate and service and Hank is the only janitor seen. Therefore, it's likely that he has a significant engineering background with the attendant high proficiency in math.
Vincent’s big brother Chad is revealed to be a geek despite all the praise the other kids initially had for him. Since he was a geek his peers most likely didn’t want to hang out with him. Chad is shown to be very self-confident, so rather than try to impress them he would talk to and play with the younger kids. Having an older kid be nice to you when you’re very young is a big deal, so he was legitimately cool in their eyes at the time.
In Mikey's Pants, Gretchen gives Mikey pants made from a titanium alloy that the Soviet Union used on their spaceships... but the pants rip anyways. However, the Soviet Union not only went through a lot of shortages but also tended to have faulty technology, what with Soviet televisions literally exploding. Either a material shortage or terrible production left Mikey with defective pants. (Plus, why would the Soviet Union spend resources from its space program, that is, its greatest strength, on mundane pants?)
In "The Big Prank," Randall gets pranked with oatmeal in the beginning of the episode by T.J. You think he'll be quick to tell Ms. Finster about this but he decides to go to King Bob instead. Why he do this? Because he knows that Ms. Finster would just give T.J. detention which is something he literally sleeps through. By going to King Bob, Randall knows that King Bob may give T.J. a punishment that is more humiliating or painful (like being given a swirly or taken to the dodge ball wall) as Randall was furious at T.J. at the time.
In the film Gus gives Spinelli command of the “Special Forces” (aka The Kindergartners). This makes sense since not only is Spinelli considered the toughest kid in school, she was their leader briefly during the episode “The Break-Up”.
Considering the fact that in the film, it's shown that Prickly and Benedict were faculty at Third Street School in 1967 (Summer of Love), and that it's been thirty years since Benedict was fired from his position as principal for his extremist idea on banning recess, it can be inferred that the film is set during summer vacation in 1998, fitting with the fact that the show originally debuted in late August / early September of 1997, right around when schools in the US and Canada begin their school years.
Miss Finster Took a Level in Kindness between seasons. Why? Remember that Spinelli rescued her cat, and then the gang found her a cute kitten to adopt. It's possible that part of the reason she was grumpy was that her cat may have been sick or getting on in age, and she felt better after helping rescue one of Stella's babies. She also saw Mikey earnestly defending a cat mother, and she could respect that.
Stinky Peterson is mentioned twice. Once in "My Fair Gretchen" and again in "Gus' Fortune" both events could easily be connected since he probably went to the mall after school on the day he aced the test then found the paper fortune teller there and got the "eat, drink, and be merry for tomorrow is your final day" fortune that Gus also got. Then the next day, he was taken to Principal Prickly's office and told about Oppenheimer then passed the board's questions thus making it his final day at Third Street Elementary.
"Operation Stuart" takes place after "The Trial", and Spinelli is a bit dismissive of the cat when she's found. Ostensibly because Stella jumped on her face when she opened the can, but she's also remembering that helping a cat previously got her into trouble with the other kids.
Hustler's Apprentice shows that the Hustlers have standards - but why sell fake School IDs? This might be a case where he will make an exception, as technically Spinelli is removed from the Ashleys within the rules.
At the beginning of "Yes, Mikey, Santa Does Shave", the main gang (minus Mikey) reminisces about how excited they used to get about Christmas and Santa Claus when they were little. But T.J. doesn't join in the reminiscing; he only remarks on the fact that now they've all outgrown their belief in Santa. This small detail fits with the fact that later, T.J. plays "Harvey Hanukkah" in the school pageant, indicating that he's Jewish. He presumably has no Christmas memories to share because his family doesn't celebrate Christmas.
At the end of "Germ Warfare," when Gretchen comes back to school after being Out Sick, her voice has less Nerdy Nasalness than usual. The cold medicine she took must have also temporarily relieved her allergies that presumably cause her usual stuffed-up tone.
In "The Candidates," when Gretchen protests that kickball has nothing to do with being a good president, she exclaims "Why, FDR couldn't play a lick!" Of course he couldn't play kickball – he used a wheelchair.
Ashley T. has always been the quietest and the least mean of the Ashleys who just does whatever the others do. This starts to make sense when "Chez Vince" when she's hinted to be a Closet Geek who likes comic books: She's more introverted than the other Ashleys and can probably empathize with the less cool kids. She likely keeps that side of her to herself and goes along with the group to fit in.
Dr. Slicer, his treatment of his students and his Nazi-like behaviour raises few uncomfortable questions: 1) Considering his personality, cruelty and his methods what knows what could have happened if Slicer would have taken over Third Street School and remember that he made TJ (who always stands up to adults and rebels against their evil behaviour and students are always win because of him) afraid and unable to rebel, 2) What if he was the principal of the other schools and what could have happened in those schools, 3) Considering his Nazi-like behaviour, he may be worshipping Nazis and Hitler.
It’s made slightly worse when all of the students have to explain that Slicer nearly took control when they’re asked about how their day went. Sure some parents in the series may think their kid is overreacting about it but not exactly all.
In The Movie, Benedict's plan to destroy Summer is bad enough from a kid's point of view, but then you look at it as an adult and realize that he was effectively trying to restart the Ice Age, which would almost certainly destroy civilization, if not humanity in general. All for the sake of test scores.
Considering Gus's dad is in the military, he's more than likely going to move away from Third Street at some point and leave the best friends he's ever had like he's had to several times before.
In "Recess is Cancelled" TJ refuses to do anything about the governments plan to cancel recess on the grounds that it's unpatriotic and that's the one thing he'd never do. So basically TJ would never fight or go against the US government, no matter how wrong he thought they were, because of his blind loyalty to his country. Let's hope he grows out of that mentality.
Let's hope the events of the episode have encouraged TJ to take authority figures, even those representing his country, with a grain of salt.
The Reveal at the end of "The Trial" is much more disturbing from an adult perspective than from a kid's. Randall hit himself on the head with a rock to frame Spinelli for throwing it at him, just because he was jealous that Miss Finster praised her. Thankfully it was only a small rock, since the big one he originally wanted to use was too heavy to lift, but what if he had managed to throw the big one? It's only dumb luck that he didn't seriously injure or even kill himself. That boy needs therapy!
In "Speedy, We Hardly Knew Ye," the realization that there was more than one Speedy is kicked off when Spinelli notices that the dead Speedy has a spot under his chin that she never saw before. This might imply that there were two different Speedys during the current school year; that the hamster the gang first got to know had already died and was secretly replaced by Miss Grotke. Given how short a school semester is, this would mean that the Speedy seen in the episode probably only lived a few weeks or months after Miss Grotke bought him. So either she mistakenly bought a hamster that was elderly and close to death, or he died young of some illness that no one noticed.
Gus's corruption in "King Gus" is even worse in light of "Dodgeball City." Before the events of the series, he gave up dodgeball out of guilt that he accidentally hurt a little kid with a ball he threw. Yet as king, when the other kids revolt against him, he has his supporters throw balls at them!
. Either a material shortage or terrible production left Mikey with defective pants. (Plus, why would the Soviet Union spend resources from its space program, that is, its greatest strength, on mundane pants?)