During the train scene, Gromit is dangling from a lamp on the ceiling. Then Feathers McGraw shoots the lamp, Gromit falls onto the train, and the lamp is on his head. But as earlier seen, there is a light bulb in the lamp, so shouldn't we have seen and heard breaking glass?
When Gromit is in the Techno-Trousers and painting the ceiling of the spare room (upside down), Wallace backs out into the upstairs hallway and bumps into Feathers. Feathers is not there until Wallace bumps into where he is supposed to be standing.
When Gromit is getting ready to go into the bathroom in the morning, Wallace passes him fully-clothed and says, "Lovely morning, Gromit." The next shot shows Wallace back in his bathrobe blow-drying his bald head.