Derek is talking to Addison as he wraps the earphones around his iPod and places it in the pocket of his lab coat. When he stands up, the earphones are around his neck and the iPod is clipped to his waistband.
When Burke and Cristina are walking along and Burke asks her if there is anything he should know about her religious holidays, you can see crew members, a boom, and a stage light reflected in the glass running alongside them.