Adaptation-Induced Plot Hole: Armstrong and Hughes are both stationed in Central, and it's reasonable to assume that the Elrics are just passing through (the trip to Liore is mentioned). But no attempt is made to explain why Mustang is there and acting as an authority figure, particularly as his later transfer from East to Central is treated as a major career event.
Ed's is pressed when McDougal brings up the brothers' human transmutation incident.
Bloody Murder: McDougal can use is own blood as a weapon by freezing the water in it.
Canon Foreigner: Isaac McDougal did not appear in the manga.
Establishing Character Moment: Apart from the foreshadowing about "the shape this country is in" (which does get a callback in a much later episode) this episode exists largely to display these for most of Brotherhood's major characters.
Filler: Unusually for the first episode of a series, the storyline and main antagonist of this episode are completely original to the anime. The manga's own establishing character moments for the characters who appear here are repeated later when those characters were originally introduced in the manga (including the framing of them as new, important characters), creating quite a bit of redundancy as well as some premature spoilers.
McDougal's use of the city as a transmutation circle and his Motive Rant basically lay out the Evil Plan happening in Amestris. The shot of the citywide transmutation circle will show up later, too.
Bradley immediately demonstrates that he is a deadly combatant with an innocuous public face. The manga took much longer to lay out his true nature, showing him first as eccentric, but competent until the events of Dublith.
Lust (and Gluttony) are both in The Stinger, with Lust remarking that McDougal was one of their possible sacrifices.
Gory Discretion Shot: The first guard is killed on-screen when all the water in his body is flash-frozen, and he shatters when he falls. McDougal's second victim gets to be flash-boiled. This time, the camera stays on McDougal's face.
Harmless Freezing: Subverted with the soldiers that McDougal uses his freezing technique on; it is clearly lethal.
Heart Is an Awesome Power: The writers got really creative in the various ways a state alchemist could weaponize water: creating ice walls, steam clouds for camouflage, and then going into all the ways it can be used on and from the human body—repeatedly pointing out that the human body is mostly made of water.
Making a Splash: McDougal can make water boil and freeze as he wills.
Person of Mass Destruction: McDougal creates huge walls of ice, which he uses to try and freeze over Central.
