Factual error: After they finally start spending money, and after you see them in the older model black Mercedes Benz S-Class, you see clearly a newer model silver Chevrolet Corvette ('05-'09), even though the scene is supposed to be taking place during the latter part of 1996 or early 1997.
Factual error: Many of the songs featured in the film, almost all of which are portrayed as being singles actually being played by the disc jockeys, came out after the 1966 setting of the film, including Procol Harum's "A Whiter Shade of Pale" (June 1967), Tommy James and the Shondells' "Crimson and Clover" (November 1968), The Who's "I Can See For Miles" (October 1967), Jimi Hendrix's "The Wind Cried Mary" (May 1967), the Turtles' "Elenore" (November 1968) and Herb Alpert's "This Guy's in Love with You" (April 1968) among several others.
Factual error: As Eliott walks across the hillside where the concert is taking place, you can see nylon dome and bivouac style tents. Tents made with metal poles and nylons didn't come to market til the 70s. (01:23:05)