Continuity mistake: In the scene where Donna, Kelso, Eric, and Hyde are in The Hub after Eric Gets Suspended, Donna gets mad at the guys and leaves. But two shots later when Hyde is seen smiling and sipping his soda, you can see Donna's hair on the left side of the shot as if she was still sitting where she was before. (00:03:00)
Donna and Eric Sleepover - S2-E8
Continuity mistake: The design of Forman's Spider-Man sheets are of the Spider-Man from the late 1990's cartoon.
Continuity mistake: When Jackie leaves the basement and Lorie comes down she's wearing green pants, but as soon as she walks away they're blue jeans. The shirt, jacket are the same, but it's the pants that change.
Garage Sale - S2-E1
Continuity mistake: At the movies, Fez is daydreaming. Jackie's hand comes into frame as she's about to reach into his popcorn bucket. The shot cuts and her hands are at her side. She subsequently repeats the action.
Moon Over Point Place (1) - S2-E26
Continuity mistake: Red, Kitty and Midge are talking to Bob about Eric and Donna having sex. Red makes a point and Midge turns her head to look at Bob. The shot cuts and we see her from the side, repeating the head turn.
Answer: It's Ashton Kutcher's dog.