Factual error: The flashback where it shows him flying to New York shews the Twin Towers, but also 432 Park Ave which was built after the world trade center was destroyed. (00:11:42)
Factual error: In the scene where the camera shows Times Square, visible on the right of the screen in the front of the shot is a poster for the Broadway show "The Lion King". The Lion King just celebrated 10 years on Broadway and was not playing in 1994.
Continuity mistake: When Summer is singing in the park, her hair changes from in front of her shoulder to behind her shoulder in between shots.
Factual error: Throughout the movie, which mainly takes place in the early and mid 90's, the cars that are seen are from the late 90's and early 2000's. The easiest to spot are the taxis, which are the 1998 and above versions of the Ford Crown Victoria.
Continuity mistake: While out to dinner with William, Summer has her wine glass in her hand one minute, and when the shot changes her hands are under the table - too quickly for her to have put the wine down.
Continuity mistake: In the scene where April and Will are having the smoking contest outside of the bodega, the hand that April is using to hold her cigarette changes several times from shot to shot.
Character mistake: When Will finds April's lost copy of Jane Eyre, the book shop clerk reads the inscription written by April's dad and says it's a quote from the book. It's actually a quote from Bronte's poem Evening Solace.
Factual error: In the first coffee shop scene, after the time leap to 1997, the song in the background is "The Boy with the Arab Strap" by Belle and Sebastian, from the album of the same name, which wasn't released until September 1998.
