Deliberate mistake: When Quinn is texting the boy next door, he responds too quickly for it to be real. She sends the "So you think I can stop traffic, huh?" text and gets a response within literally two seconds. She then sends the "Did I wake you up?" text and gets two responses within five seconds. Texts usually take several seconds (at least) to be delivered and opened, so even with great service and lightning-fast fingers, this is obviously far too quick.
Continuity mistake: When Specs and Tucker first arrive, pay attention to the cupcake Tucker is eating. When Tucker says "Thanks little man, some of my best editing on that one!", the cupcake still has frosting on top and he begins to peel the wrapper from it. The film cuts and suddenly there's no more frosting, nor is his hand still removing the wrapper. Then, over the next series of edits, the amount of frosting on the cupcake and the amount of cupcake left in his hand changes repeatedly.