Revealing mistake: Just before Hermie goes into the drug store to buy the condoms, you can see his breath when he is talking even though it's supposed to be summer time.
Summer of '42 (1971)
1 revealing mistake - chronological order
Directed by: Robert Mulligan
Starring: Jennifer O'Neill, Gary Grimes, Jerry Houser, Oliver Conant
Factual error: When Dorthy comes to sunbathe on the beach, mountains of approximately 500 feet in elevation are seen but Nantucket Island's highest elevations are in the 100 foot range. (00:14:55)