While the story takes place in Pittsburgh in the early 1990's, whenever Charlie, Patrick, and Sam go through the tunnel into the city, you can see "Consol Center" on the road sign. The Consol Center was built in 2008.
Mr Anderson claims that it was Charles Dickens who left a character literally hanging by his fingers in a serialized story, thus contributing to the term "cliffhanger." In fact, the author was Thomas Hardy, in his 1873 serial novel A Pair of Blue Eyes.
Early in the film ,when Charlie gets dropped off at his home at night after a ride from Sam & Patrick, Charlie's 2 car driveway is empty. When Charlie walks into the house, he overhears his sister Candace and Derek having an argument in the living room. When Derek leaves the home a few minutes later after the fight, he's shown getting into his car and driving away, which was not there a few minutes earlier, although Derek was already in the home.
Whenever The Beatles' record "Something" is shown in closeup it has a plain red label. The label should be that of Apple records, their label in 1969, the year the album "Abbey Road" (containing that song) was released.