Continuity mistake: When Walter walks in on Brittany in the bathroom, the bubbles on her body change from shot to shot. In one shot, there are many bubbles around her bust, in the next, they're all gone, and reappear in other shots. (00:24:00 - 00:24:55)
Continuity mistake: When Walter is looking for the condom in his drawer, he pulls out a picture of a girl and some cylindrical object and puts them on the desk. The items change position in the shot where he turns his back to the camera. (00:52:40)