During scene set at LA hot dog stand in late Seventies, huge wall menu in background reflects 2000 era fast food prices and even lists at least one soft drink not introduced until years later.
At the last scene at Okie-Dog, the lid on Casey's orange juice disappears between shots.
At the end of the film, Pat is seen watching a news report of John Lennon's death, which is intercut with scenes of Darby preparing to OD. Darby died almost a whole day before Lennon's assassination.
While The Germs play their show at the Orpuim, Darby Crash throws powdered sugar at The Damned for their harsh remarks. In the scene before Darby grabs the sugar you can clearly see that the lead singer of The Damned is already covered in powdered sugar.
After being kicked out of the Orpium for messing up stage equipment, The Germs introduce themselves as Darby Crash and Pat Smear even though at the time The Germs hadn't come up with their stage names yet.