Other mistake: When the assassin disguised as Hugo frees himself after being arrested, he escapes into the adjacent room, closely followed by firing FBI agents. There, he masters the remarkable task of taking off his wig, his mask, his trousers, his jacket and the bloodsoaked white shirt and stashing it all under the bed within two seconds.
Other mistake: The assassin disguised as Hugo shoots the black man cleaning up the mess in the back. The black man turns around to be shot again and hurled out of frame. How come the first shot does not elicit more than a slight wince from the black man, but the next shots are powerful enough to let the overweight man fly?