(500) Days of SummerGoofs
In the split shots from the Expectations/Reality scene Summer wears an engagement ring in the Reality point-of-view, which is seen first when she hugs Tom at the door. When he enters the apartment the shot is the same for both Expectation and Reality and in both Summer is no longer wearing the ring.
Errors in geography
In the final scene with Tom, Autumn refers to the park bench location as "Angelus Plaza", which is at West 3rd and S Hill St in downtown LA. The precise location of the park bench and view from it is one block south of that, at a greenspace at West 4th St and S Hill St, next to the California Plaza Watercourt and directly adjacent to Angel's Flight Inclined Railway Station.
On day 303 early in the film, Tom receives an e-mail from Summer that she can't meet that week and hopes that means he's ready to be friends. The e-mail is dated May 7, 2008. On Day 500, Tom awaits an interview and the narrator says it was May 23. This is inconsistent with the rest of the movie which seems to be set in 2006 and early 2007.
Tom and Rachel are shown playing on a Nintendo Wii game console on day 11. Near the end of the film, the narrator says day 500 is Wednesday, May 23. The last time May 23 was a Wednesday was in 2007. Counting back, this means day 11 would have been January 18, 2006. The Nintendo Wii was not released until November 19, 2006.