During Shelley's speech before the council to recruit pledges for ZETA, she turns toward the ZETA's and Mona gives her a thumbs up. At that moment a microphone can be seen at the top/left of the screen.
During dinner, Shelly mentioned her butt to Oliver several times and even mentioned that she didn't have any tan lines. However when Shelly was walking around the house naked earlier in the movie, tan lines were definitely visible.
Right near the end of the film, when the house girls are discussing Shelly, while removing their makeup at the makeup table, Rumor Willis [Joanne], looks up into camera just as she goes off the left of the frame.
Lily was established as the one who never talks at the beginning of the movie. Yet after Shelley says she had lived in the Playboy mansion, Lily whispers something in Harmony's ear, presumably in her British accent, so why are the Zetas later surprised that she spoke and is British?
During the scene when the sorority girls are on the lawn talking about boys, Emma Stone's character Natalie has her glasses on for most of the scene, but for one shot back to her they are off, and then the cut back scene they are magically back on again without her arms even moving.
In the sorority car wash scene, Natalie deliberately turns the water hose on her shorts. At first, the wet area is very large and soaked but when the camera cuts away for a fraction of a second and cuts back to her, the wet area shows just a few traces.
When Joanne (Rumer Willis) starts running towards Steve (Tyler Spindel) with her brace on, it breaks off and you can see it behind her. When she finally catches up to Steve the brace it is no longer behind her. Then when it zooms up to Shelly, you cannot see the brace in the direction she's looking.
When Shelly stands up from the curb to follow the sorority girls that are talking about a party, she is wearing 2" wide hill shoes. When she is walking into the sorority building you can clearly see that the hills are slimmer.
When Shelly gets out of jail and is sitting on the curb doing her make-up some college girls walk by discussing a party. The girls are walking behind Shelly and towards camera right. When Shelly spies on them through her make-up mirror, the girls are walking towards the right of the mirror when they should be walking towards the left.
In the opening shot of the movie, Shelley is walking beside the swimming pool of the Playboy Mansion. She walks past two Playmates having a conversation while standing at the edge of the pool, Hiromi Oshima, wearing yellow shorts, and Sara Jean Underwood. Shelley then hugs Playmate Lauren Michelle Hill who is standing next to lounge chairs. When Shelley turns around to yell over to Hugh Hefner and the Girls Next Door, who are sitting at the bar. Hiromi, now wearing white bikini bottoms, and Lauren are standing blowing bubbles behind Hefner and the Girls Next Door. Then Shelley turns around to walk down some stairs next to the pool. Hiromi, with the yellow shorts back on, and Sara Jean are following Shelley several feet behind her while Lauren is standing in the background next to the lounge chairs.
Everybody acts surprised when Lily speaks, especially because she's British but earlier in the film she whispers in Harmony's ear, no one acts surprised when this happens, meaning that she often whispers to people so they should already know she speaks with an English accent.