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 Wallace is being dressed by the machine in the morning, it puts his sleeves on first, then his shirt and cardigan combination. When Gromit is sitting in the seat later, the machine puts on the shirt and cardigan first and the sleeves afterwards.
The close-up on the box of spare track segments that Gromit picks up shows that all the segments must be straight. However, Gromit uses these segments to guide the train round a 180 degree curve and to slalom round the legs of the table and chairs.
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.
When the robot claw on the end of the long metal rope emerges from the motorcycle helmet on Wallace's head, it is clear that it is far too large and there is far too much metal rope to fit inside the helmet together with his head.