When Quinn gets Jake's good-morning text, her phone date says March 21. Minutes later she finds out on January 21 that Ms. Ramirez no longer works at Duke. Then the day of the Work It competition, Quinn's alarm goes off and the date is again March 21.
Jake steps in during the final routine because Quinn is late, but he stays in the routine when she comes back and seems to have his own positions to stand or dance in, such as when the group is in a line and he's in the middle. None of the dancers seem to be displaced, even though he should not have been in the routine. This is confirmed after the performance when Quinn makes a comment to Jake about dancers who have graduated not being able to perform.
When Quinn calls Veronica on her phone from the library, her iPhone screen is completely grey-ed out. She's not even on a real call.