Why did Lothor only bring only bring Zurgane back with him? Choobo was incompetent, Vexacus and Shimazu both couldn't be trusted, and Motordrone was a machine.
Why does Tommy's morpher have a key? Because his last set of (original) powers was Turbo, and they had keyed morphers as well.
Mesogog's unusual speech patterns could be explained by Anton having both Multiple-Personality Disorder and Asperger's Syndrome. If Anton had Asperger's syndrome to begin with, then when he had a physical transformation, it wouldn't have necessarily had to rewire his brain. In other words, it would have been Anton inside of Mesogog's body. So why would Mesogog have acted like a different person? Multiple-personality disorder. Anton created the alter-ego of Mesogog after the trauma of seeing himself as a monster. Mesogog was his repressed hatred and paranoia, possibly from Asperger's syndrome itself, since the disorder can be accompanied by paranoia\depression\schizophrenia. If that were the case, then Mesogog would also have Asperger's syndrome, and his speech patterns would simply be a variance on that.
The Evil White Dino Ranger's Phlebotinum Breakdown is the result of the Morphing Grid not being able to handle two White Rangers. This is the infamous "Too much pink energy is dangerous" line in action.
Trent's refusal for help initially is his mentality that he's a superhero and that superheroes never need help.
Also, Tommy needing to learn to fight for his own life is a reflection of one of his more subtle traits in the old days - guilt over his actions while under evil influence led him to be willing to stick his neck out very far indeed for others, yet reluctant to have anyone else risk themselves for his sake.
Why did it take the raw power of the Dino Gems to defeat Mesogog? Well, Mesogog wants to bring the world back to reptilian domination, just like when dinosaurs ruled the Earth. Now, what helped kill the dinosaurs? A meteor, of which the Dino Gems are fragments of.
Problem: The Dino Gems got their power from being what wiped out the dinosaurs, by your logic they should have gained power from destroying Mesogog.
All of the Dinozords are named after real dinosaurs or prehistoric beasts... except for the Dragozord (dragon). This seems weird... until you realize that, up until the past couple centuries, dinosaur fossils were often believed to be the bones of dragons! That, and dragons actually exist in the Power Rangers Universe. Usually in the form of zords, but a purely flesh-and-blood one appears in Power Rangers Time Force, "Beware the Knight", and another featured in Power Rangers Mystic Force.
Tommy wears long sleeves in every episode of Dino Thunder because Jason David Frank has tattoos on his arms. The reason this is Fridge Brilliance is that, if the character of Tommy Oliver PhD. has the same tattoos, he'd likely cover them to teach High School. That doesn't explain why he wears long sleeves even when not working; but hey, this was Disney.
In the first few episodes (before he gets the Black Dino Gem), Tommy wears red. What was the last color he had? Red!
There's a lot of symbolism regarding the fighting of the past Ranger forms Tommy had. First off, he goes backwards from Red Zeo Ranger, White Ranger to Green Ranger. Looking at it, Red Zeo was when he officially became leader of the Power Rangers, White Ranger was his resurrected Ranger form and the Green Ranger was the form with the most regrets/struggles he had to go through. This is also backed up with the scenery. Red Zeo is in a desert with water, White Ranger has a bare forest, and Green Ranger is a beautiful forest with fallen pillars. This represents his struggle in being a ranger because as time went on, the battle of good versus evil was putting a big strain on him and the landscape was a reflection of his own mind.
The Red Zeo Ranger fight taking place in a desert could connect to the time Tommy was brainwashed into leading the Machine Empire in a colosseum within a desert.
A small one in the Ninja Storm team up episode - as they prepare for the big Ranger-on-Ranger showdown, Conner says 'they use special powers, we use special powers'. In two fights - Conner v Shane, Ethan v Dustin - the Dino Thunder Rangers use their powers first and in Tori v Kira, they were used at very nearly the same time. Why? Because the Ninja Rangers had been needled about honor in the Cyber Cafe, and even when evil, they still held themselves to a standard.
Tommy having the civilian power of invisibility while Trent has the civilian power of camouflage can highlight the similarities in their plot lines, being corrupted into evil rangers then slowly taming their power to join their friends as heroes, since they function the same way by hiding the users from sight.
These particular civilian powers can also be tied into their respective characterizations, where Tommy Oliver (related to the post below) is basically so defined by his time as a Power Ranger that Tommy Oliver the person is basically invisible; who is Tommy Oliver without the powers by this point, which plays a huge part in his comatose arc. Trent's camouflage ability is similar in the sense that he's not certain of who he is, but whereas Tommy's identity was subsumed by spending years in a neverending battle against evil, Trent's identity is forced to blend in with the desires of his emotionally abusive father, basically always having to avoid showing who he really is and only being able to be himself once he and his father grow beyond that point.
Tommy being in Ranger form for half the season is a nice bit of Irony given that staying morphed was a problem for him when he was the MMPR Green Ranger. It also reflects how being a Power Ranger has come to so thoroughly define his life as discussed by Linkara in History of Power Rangers.
One crossed with a bit of fridge horror from "In Your Dreams". Why was Trent the only one who stayed at Hayley's instead of going home to bed? Because he was trying to avoid Mesogog whose influence on Anton was getting stronger.
In "Legacy of Power", Hayley comments that Mesagog must be incredibly smart for a mutant freak to be able to block her hacking skills. Considering Mesagog was actually Dr. Anton Mercer, she was more right than she knew.
Pretty much everything about Tommy in this season when you think about it:
Firstly, he's living all alone in a cabin the woods. The last time we saw him living like this was when he was depressed about losing his Green Ranger powers. Throughout Dino Thunder, we never see Tommy with any adult friends outside of Hayley implying that years of having to interact only with fellow Rangers has made it difficult if not impossible to befriend anyone who isn't a Ranger, and we don't know if he is still in contact with any of his former teammates.
The Tyrannodrones were created by Tommy and Anton and reprogrammed by Mesogog to serve him and him only. Tommy essentially helped create his own equivalent of the Clone Troopers and the only reason he didn't get a chance to control them was because they got Order 66'd much sooner.
In "The Missing Bone" we learn that Anton and Tommy created a monster that can mind control people. Think about that. Tommy Oliver, the most well known example of Brainwashed and Crazy in the Power Rangers universe, created a creature that strips people of their free will.
In Tommy's defence, he probably didn't intend for the monster to be capable of that when the experiments started.
Kat's absence from Dino Thunder suggests she and Tommy broke up some point between "Passing The Torch" and Dino Thundernote Though their return in Power Rangers Ninja Steel implies they are back together while Mighty Morphin Power Rangers: Once & Always outright states it, confirming onscreen the Soul of the Dragon comics storyline that has her as Tommy's wife and JJ's mom.. Was Tommy's unethical and possibly illegal experiments with Mercer a cause for their relationship to end?
In "Burning At Both Ends", Tommy threatens to kill Trent who is not only Brainwashed and Crazy but is a teenager just like Tommy was once. And given Tommy does kill Zeltrax who Was Once a Man twice in the season, there's a good chance he wasn't bluffing.
Jackie Marchand herselfconfirmed in a tweet shortly after Jason David Frank's death that "Fighting Spirit" was all about fighting one's inner demons. that he sees not just the Green MM Ranger, but also his White MM and Red Zeo Ranger forms as representations of his demons is gut-wrenching, when you consider that these two, especially White, was him mostly having broken free from the darkness that the Green Ranger still represented to him. Tommy is pretty much disassociating at this point, and being stuck morphed probably was aggravating it, and ironically, he was able to mask it as clearly as a Ranger's helmet should mask their face.
shortly after Jason David Frank's death that "Fighting Spirit" was all about fighting one's inner demons. that he sees not just the Green MM Ranger, but also his White MM and Red Zeo Ranger forms as representations of his demons is gut-wrenching, when you consider that these two, especially White, was him mostly having broken free from the darkness that the Green Ranger still represented to him. Tommy is pretty much disassociating at this point, and being stuck morphed probably was aggravating it, and ironically, he was able to mask it as clearly as a Ranger's helmet should mask their face.