When Cheryl, Renee, and Jazz are having a water fight in the kitchen, Cheryl and Jazz alternate between having their bikini tops on and being topless between shots.
When Cheryl confronts Bert, in frontal shots of her some of her hair is hanging over her right breast, but when seen from behind, it's all behind her back.
At the party, where the two girls are peeking in the door at the couple having sex, and then laughing in the hallway, the shadows of two boom mikes are clearly seen on the wall.
Two bikini babes make fun of Chester for leaving the lens cap on his camera, but he surely would have noticed that since he wouldn't have seen them with the SLR they gave him.
In the scenes at the party, where the two girls are peeking in the door at the couple having sex, and then laughing in the hallway, the shadows of two boom mics are visible on the wall.