Other mistake: When Rowan Atkinson is riding in the train, near the end of the film, he is looking out the window. He is looking forward, then quickly looks backwards. He does this several times in a row, as if trying to see things quickly as the train passes them. But, when the camera pulls back, Rowan's back is facing the direction the train is moving, thus he was looking the wrong way! You can tell by the way the scenery is moving as you look through the window.
Other mistake: When everyone is on the road leading to Silver City, near the end, about four of them are behind one another on the road. When it cuts to the radar owned by Sinclair, it shows all of the dots (which represent the people) all spread out around the big star which is train station, when in fact the dots should all be in a line behind each other, just like they are in the cars.
Other mistake: When Hitler's car is getting destroyed, the shot of the muffler falling off the truck is the exact same shot used for when Rowan Atkinson and Wayne Knight were in the van. This is most notable because the bikes disappear and the car isn't even Hitler's car, it's a white van.