Continuity mistake: In the laundry room when Penny is talking to Sheldon, Sheldon takes some time arranging a blue shirt on his plastic laundry folder. Then it suddenly turns into a pair of socks, which he folds and then picks up the blue shirt again. There was not enough time for him to switch out the shirt for the socks.
Continuity mistake: When Sheldon emerges with all of the bath item gift baskets for Penny, he drops them on the floor and chair. Between shots one of the baskets on the chair changes from being an upright green-ribboned basket, to a toppled-over white-ribboned basket.
Continuity mistake: Near the start, when the camera is on Raj, David Underhill is seen in the top left-hand corner of the screen shaking someone's hand, already in the cafeteria. Then, when the camera is on Wolowitz, David is just walking into the door of the cafeteria. David sits down to the right of the man sitting at the table, then shortly afterwards David is now sitting where the other guy was, originally.
Continuity mistake: In the opening scene, just after Howard says, 'Creepy good or creepy bad?', there is a shot where Howard is holding his food, even though Leonard hasn't given it to him yet and it isn't there in the shot before or after. After Leonard gives the food to Howard, the exact same shot is used after he says, 'I'm not necessarily talking about the food', so the shot was taken from there and it is shown twice.
Continuity mistake: When Leonard and Raj are getting ready in the bathroom, Raj picks up a tube of shampoo/conditioner off the bathroom bench with his left hand. However, in the next shot, Raj has nothing in his left hand and the tube is back on the bench, with no time for him to replace it between shots.
Continuity mistake: When Leslie and Sheldon are talking to Dr. Eric Gablehauser in his office, in one shot Eric throws a piece of paper onto the desk behind him (next to the computer.) Through the rest of the scene, this piece of paper keeps changing position.
Continuity mistake: Right at the start of the episode, Leonard kisses Penny. When he starts kissing her his head is tilted to the right (opposite side to the wall with the camera). When they move to the camera image, his head is tilted to the left (on the side with the camera), and when they move back his head is back tilting to the right again.
Continuity mistake: When Sheldon goes to speak to Leonard, he is sitting on the couch. Camera cuts to Raj for one second, then to Penny and you can see Sheldon has crossed the apartment and is now in the hall. There is not enough time to move that far in that time.
Continuity mistake: When Penny finds out about the expedition, Sheldon starts to walk to his apartment. Camera cuts to Leonard in the apartment for five seconds and then to Penny in the doorway. Behind her, you can see Sheldon walking to the apartment still. Since he was halfway to start with, he should be in the apartment by now.