Question: Why didn't Corey Feldman reprise the role of Donatello for this movie?
Question: Why did Splinter make Michelangelo do flips after he jokingly said, "All the good ones end in O" to Keno?
Answer: He's punishing Michelangelo for disrupting the session with Keno, which he used as an opportunity to diss Raph.
Question: It's revealed that the ooze came from TGRI but, what were they planning on originally doing with it before they decided to dispose of it?
Answer: If you pay attention to the professor's explanation (starting at 0:55:55) he says "An unknown mixture of discarded chemicals was accidentally exposed to a series of radiated waves and the resulting ooze was found to have remarkable but dangerous mutanagenic properties... on our way to bury them a near collision caused us to lose one of the canisters down a sewer 15 years ago." Basically, "we had an accident and the results were dangerous and unpredictable, so we immediately went to dispose of it all." So there actually were no plans for what to do with it at all.
Question: In the TGRI lab, when the Professor is disposing of the Ooze, he places it in a weird looking machine. It has a pyramid like structure with what appears to be a rock of some sort in the center. What is that machine and what is that rock? If it even is a rock? (00:23:05)
Chosen answer: The machine dispose of the ooze. How exactly is not expressed in the film.
Question: Does anybody know how soon this movie takes place after the first one? The foot soldiers are regrouping at the "fallback spot" and Shredder digs out of the garbage pile which would suggest anywhere from 2-24 hours later. Yet somehow April has a brand-new fully furnished apartment and it sounds like the turtles have been there for weeks by the manner in which the neighbor complains about the noise.
Answer: Shredder could have been unconscious for days before he even began to dig his way out. Also, some apartments come furnished. The neighbor is likely one of those neighbors that always has to complain about something, and exaggerate at that. It's probably been about a week or so.
That still doesn't explain the scene with the foot clan.
Answer: Maybe they went into hiding for a while before meeting at the junkyard. It's unlikely they'd be remembering where to go after a huge battle from the previous TMNT movie. It was hectic after all.
Question: Looking at how this movie opens, it is the same night the first film ends. April's apartment burned down. How could she have a new, fully furnished apartment for the turtles to stay in? It's hinted that she has been there for a while based on the neighbor's comment about her "aerobics."
Answer: Who said or hinted it was the same night as the first one ended? It's a night shortly after the first movie. Regarding the new place, well that's what insurance does – provides you with a new place.
I also think that it is the same night. The foot soldiers are still in their uniforms and show fresh signs of battle. Plus, when the garbage truck pulls away, we see Shredder lift his hand from that area, which tells us that he was just "dropped off" for lack of a better term. But mostly, the dialogue between April, the turtles, and Splinter indicates that they have been crashing at her place for an extended period of time, not just a few hours or days.
Question: How did Shredder escape the back of a garbage truck after it was turned on by Casey Jones?
Answer: He didn't escape. He just managed to survive somehow. Hence, we see him escaping at the dump after the truck drops off the garbage.
Then how exactly was he not crushed while inside a garbage truck?
People have survived (badly injured) in real life. Being crushed in a garbage truck is very dangerous but can be survivable depending on how much and what sort of garbage is in there, when the victim gets rescued and what medical care they get afterward. Also Shredder is a movie supervillain in armour so he is stronger and better protected than the average person.
Answer: Because he was in rehab at the time.