In "Failure to Communicate" (Episode 2 at around 20 minutes from the beginning). House and Stacy sit in the airport hall when House starts to talk about a sales clerk and her disease.

When he starts talking, Stacy has a pen in her mouth while typing her laptop. The camera goes to a view from the right and the pen has suddenly moved behind her ear. Again a cut to a look right from the front, the pen has disappeared completely and Stacy's hair is in perfect order. But with the next cut to the side the pen is back behind her ear.

It's obvious the scene was recorded at least twice, with two camera-views: The pen appears from the left side and disappears at the front-side-view.