When Beca's using her laptop to remix songs while she's sitting on grass at the first half of the film, the camera reveals that the time on the computer is 1:13 AM. However, it can be clearly shown that through the bright scenery, the setting is either in the afternoon or very late morning.
Upon being picked up by the taxicab, Beca has four black bags/suitcases, plus her black laptop bag placed into the taxicab's trunk. Upon arrival at Barden, she grabs the laptop bag, while a yellow-shirted volunteer unloads the trunk. The bags do not follow her to her dorm, and once in the room, Beca is unpacking boxes and a brown duffel bag.
When Chloe said she just had her surgery regarding her node and couldn't sing any higher than a G#, she actually hit a mid-high C in "Just the way You are", and something higher than a G# during the finals as well.
Aubrey is talking to The Barden Bellas about rehearsal times when standing in front of a white board displaying the rehearsal schedule. Aubrey says "we will practice every day for at least two hours seven days a week..." however the board behind her clearly says under Sunday: "No rehearsals - enjoy it!"
When the guys come in to announce there's no one left to audition, Aubrey and Chloe have no one sitting behind them. The shot changes and there are 2 people sitting behind them. When Beca enters, those people disappear again.
When Chloe, Aubrey and Fat Amy are fighting, Lilly attempts to join the group and is wearing a green bow on top of her head. Fat Amy pushes her out of the way and Lilly's bow falls off. When she lands in the pool of vomit in the next shot, the bow is on her head again.
In the finals, when the Bellas are doing the stationary walk dance in a line, Aubrey's hair is clearly let loose. However, in the next scene, her hair is neatly tied in a bun again. Afterwards, she then lets her hair down.
(at around 1h 13 mins) When the Bellas are singing "The Sign", a shot of the audience shows a red-headed girl with a lavender top. Three seconds later the same girl has moved and is sitting just below the judges surrounded by different people.
(at around 1 min) When Beca is seen using her laptop right before the cab ride to Barden University we see the time 5:50 pm. Once she gets her equipment set up in her dorm room that same day(at around 56 mins) we again see the time as 5:50 pm.
During the conversation between Bumper and Benji at the student fair outside, you can see Unicycle walk away but when the camera switches back to Bumber from Benji, Unicycle is back leaning against the post as if he never moved.
When the rental vehicle runs out of fuel, a view of the fuel gauge is shown. The lights for the "Battery", "CHECK BRAKES", and "SERVICE ENGINE" are illuminated which means the key is in the ON position but the vehicle hasn't been started.
At the "A-ca-initiation", "I Can Feel It" is selected on the MacBook but "Keep Your Head Up" starts playing and even though Justin hits keys, the play button isn't actually pushed (the play symbol doesn't change to a pause symbol).
When Jesse is about to start the end of "The Breakfast Club," he turns one of the lamps next to Beca's bed off. Since there is a light on Beca's desk, the room should still be lit, but the room goes completely dark.
Just before Beca's attempt to make amends with Jesse, she turns a corner on the way to his room. As the shot begins, there is an extra "walking" down the hallway in the opposite direction; however it is clear that the extra was standing still as the shot began and started walking as Beca turned the corner, which looks highly unnatural.