Revealing mistake: When Clara is filming her kids, we see her daughter operate the car. When she's supposed to have put the car in gear and have driven forward, you can see the scenery move in the background, showing that the car was stationary and the camera was just violently moved to the right to simulate the act of the car moving.
Visible crew/equipment: The boom mike is visible in the left hand corner of the screen when Mel is talking to Bret and Jemaine in front of the store.