Other mistake: When Perceptor pops up to tell Blaster to radio Prime, Blaster acknowledges that Perceptor is there before he even sees him. And I doubt he could of heard Perceptor because of the amount of noise the lasers were making, and Perceptor didn't make any noise. (00:14:45)
Other mistake: The credits for the movie say that they are in alphabetical order, but Peter Cullen is listed before Scatman Crothers.
Other mistake: When Devastator throws a piece of the wall during the attack on Autobot city, his face is completely blacked out. Looks like they erased it and forgot to draw it back in.
Answer: The reason for this is the intent of both movies (G.I.Joe and this one) to kill off the old group and bring in a new group for younger kids. You noticed how most of the dead are from the old cartoon. The backlash was so bad that the G.I.Joe movie was changed to not kill off anyone (if you watch it you can see where characters were meant to die but the show was changed at the last sec to keep them alive. If G.I.Joe was release 1st then they would have died and if the same backlash happened you would have seen no-one die in this one.