Judith Hoag was not called in to reprise her role as April O'Neil after the director was unhappy when she derided the way they mistreated the stunt doubles and their unfair schedule changes. She stated at SuperCon Florida that she had no ill-will towards Paige Turco. Instead they met 17 years later and are now good friends. The directors found Paige Turco to resemble the character more, and found her chemistry with the Turtles to seem more sincere.
In Turtles (1990), the turtles' facial expressions were cable-operated with all the motors, servos, etc. housed in the shell. In this movie, thanks to a larger budget, the animatronics were much smaller and lighter, and were built into the face itself.
Ernie Reyes Jr. was Donatello's fight double in Turtles (1990). Producers liked Reyes so much, they created the role of Keno just for him to replace the ultra-violent Casey Jones.
One main concern that Kevin Eastman and Peter Laird had was that the second (and any subsequent) movie stay as much away from the cartoon show, and as close to the original black and white comics as possible, as the first movie did. They felt that there was plenty of material in the black and white books to form the basis for another good movie.
Kevin Eastman and Peter Laird both felt that the Shredder should not appear in the second movie. Laird even planned a scene where a garbage man found Shredder's helmet, crushed and twisted which would have been a subtle enough way to refer to his ambiguous fate from the first film and set the scene for his appearance in a third TMNT movie. However, the producers wanted the movie to be closer to the cartoon and therefore decided to have Shredder return in this movie instead.
Mark Caso: The performer inside the Leonardo costume also plays the man in the news room who tells April that Donatello is calling her.
Michelan Sisti: The performer inside the Michaelangelo costume also plays the Soho Man who talks with April before she enters to her apartment.
Leif Tilden: The performer inside the Donatello costume also plays a Foot soldier, specifically the one who says "everyone else must've been picked up" and "We all knew the junkyard was our fallback spot."