Continuity mistake: After getting the uranium, Stewie places it in the time pad and then puts the pad in his jacket pocket. After being confronted by Hitler who promises to spare them if they sing a musical number, Mort interrupts them, and it's seen that he is now standing on the time pad.
Continuity mistake: When Mort runs into Stewie's room, thinking it's the bathroom, there is a sign on the door that reads "Stewie's Room - Keep Out Brian." But a few moments later when Brian enters the room looking for Mort, the sign has disappeared.
Continuity mistake: When Mort goes into Stewie's room, there is a sign on the door that tells Brian to stay out of his room. A few minutes later when Brian and Stewie enter the room, there is no sign on the door.