The girls pull a guy's swimming trunks down, then in the next scene they're up despite the fact that he hasn't pulled them up, then in the next scene they're down again.
Reflectors visible in the girl's sunglasses at the pool side.
As Maddy is getting into the car after the party, a crew member steps into the lower right side of the frame.
Several times throughout the movie, crew members can be seen reflected in the glass framed photos hanging on the walls in the office.