Continuity mistake: Brains is writing out the notes about the emergency meeting for the carrier pigeons. He writes the first note but as he finishes writing it there is other notes already written to the right of his pad. When he gets off the chair these notes have disappeared.
Continuity mistake: Spring is dangling on a rope and he lets go of it, causing him to fall onto a bed. When the camera is on Spring on the bed, he is still holding on to the rope.
Continuity mistake: When the egg is thrown at the man in the bowler hat with two elderly women standing with him, the angle changes and a woman with a child and a dog walking behind them have appeared who weren't in the previous angle.