Kathy sets the bottle of tequila down before she and Woody walk down the hill to the dance. However, after dancing, they sit down at a table and Kathy picks up the same bottle of tequila.
When Wendell drives through the fence, the light of the car goes out, but in the next sequence the light is however on.
During the scene when Dave (Jackie Earle Haley) is flirting with the bar girl, her hand is wrapped around her cup. When Dave drops the Spanish Fly into her drink the cup is standing alone at the center of the table. In the next shot her hand is back around the cup again.
1970's and 1980's cars are seen in the background throughout the entire movie which is supposed to be taking place in the 1960's.
Towards the end of the junkyard scene when Wendell was to drive Dave out of the junkyard, there's a mid-'70s Oldsmobile Cutlass in the background.
When the guys are driving away from the market towards Mexico, and Kathy asks about the snack items they'd just stolen from her store, a bar code can be seen on one of the chip bags. Bar codes weren't introduced on retail products until the 1970s.
When the gang is on there way to Tijuana, there are present era cars parked on the street.
Although the movie is set in the early 1960s, the boys open a school locker and 1980s comic books are on the inside door. It's obvious by the DC color bullet logo.
Although it may be intended to indicate the inexperience of Kathy (Shelley Long) the usual way to do tequila shots is salt-tequila-lime ("lick it, slam it, suck it") rather than the lime-tequila-salt order she uses.