When Sarah Walker shoots the Fulcrum agent, she raises the gun in only her right hand and shoots him. In the next shot, she is seen holding the gun with both hands and the shot is mirrored. When the camera changes, it is no longer mirrored and she is once again seen holding the gun in only her right hand.
When Sarah shoots the Fulcrum agent, it's clearly shown that she has a busted lip and bruises around her left eye. When she goes back into the Buy More to tell Chuck he's safe, which is not long after, she has not one scratch on her face.
When chuck puts the bracelet on her wrist it is on her right wrist. In scene where she is about to shoot agent the gun is in her right hand, watch on left wrist. In gun close up the gun is in her l/h, watch is on her right arm and bracelet is on her left arm.
Chuck tells Sarah he's in the romantic comedy section, but in the background movies such as Jaws 3, BASEketball, and Seabiscuit can all be seen, none of which are romantic comedies.
The arrangement order of the four pens in Chuck's shirt pocket changes back and forth several times during the episode.
Lester is lying down on the stretcher wearing a neck brace and he raises up to kiss Anna. This would not be possible in real life as paramedics always stabilize someone on a back board if the stabilization of the neck with a brace is warranted. The neck brace is never installed without a back board.