Other mistake: When Dorthy is trying to audition for the Muppet's the man says they are gone and the Muppet's bus pulls up. If you look when the bus is pulling up there is no one in it, even the driver seat is empty. Then a few seconds after the bus stops Kermit and Miss. Piggy come walking out.
Other mistake: At the end of the "We Can Do It" scene, the Checker Cab the stars get into is a late model. It is definitely not the same vintage as the other 50's model cars in the movie. These cabs appear in various other street scenes.
Other mistake: Right before 'La Vie Boheme' in the Life Cafe, just after the host requests that the tables not be moved, Angel says 'Hey ROSIE, let's push these tables together.' Rosie is the name of the actress (Rosario Dawson,) the character's name is Mimi.