A Computer, a Plastic Pony, and a Case of Beer - S1-E12
Continuity mistake: When we see Sheldon in bed at the start he's either flat on his back or on his side depending on the shot. (00:03:45)
A Computer, a Plastic Pony, and a Case of Beer - S1-E12
Continuity mistake: When Missy calls Mary "Cave-mum," she has both hands up in front of her. However, when the shot changes, one hand is lowered. (00:01:15)
A Computer, a Plastic Pony, and a Case of Beer - S1-E12
Continuity mistake: Sheldon pinches a loaf of bread, but a shot later he's pinching spaghetti. This changes back and forth a couple of times.
A Computer, a Plastic Pony, and a Case of Beer - S1-E12
Continuity mistake: When the family leaves the computer store, Missy's candy sucker swaps randomly between being in her mouth or not between one frame and the other.
Answer: Some people just have a dislike for someone that can't be explained. Could be as simple as the way he's dressed.