Deliberate mistake: In the scene where the FBI agents are transporting Lester Cowans in a car and telling him all his friends have confessed, for about three seconds the scenery goes by backwards. For some reason, the shot is played in reverse.
Deliberate mistake: The window blind in Maroon's office changes to a sheet of tambour (as found in roll-top desks) just before Roger crashes through it. This was to ensure his outline remains perfectly in it, otherwise pieces would drop out which are not attached to the strings on either side. (00:23:25)