Revealing mistake: During the scene when Dawson and Gretchen are talking on the bridge, two couples walk by in the background. An older couple passes from left to right, and a younger couple walks from right to left. The younger couple is a woman with blonde, curly hair wearing a green top and beige/white skirt, and a guy wearing a green or blue top and white pants. During the same scene, the same younger couple again walks by in the background from right to left two more times. Then the older couple walks by again from left to right. Then one final time, the younger couple walks by yet again for a fourth time from right to left. Guess they were using the extras a lot that day.
Continuity mistake: When Dawson is coming down the stairs to talk to his parents in the living room, there is a shot of Gail and Mitch on the couch together. Gail is sitting in such a way that her legs are draped over Mitch's legs, and her right leg is specifically hanging over his right leg touching it. But in the next shot, they show Gail and Mitch from the other side of the couch; and suddenly she is sitting with her legs up, bent at the knees and Mitch has his right leg up. There wasn't enough time between shots for anyone to move.