Factual error: At Professor Jennings' place, the stoned Boon and Katy sing "Hey Paula." The song was only pressed in November 1962 and didn't break into the charts nationally until late December of that year, whereas the scene depicted takes place sometime in the autumn of the same year, before the song would've even been recorded.
Factual error: Bluto crushes a beer can against his forehead. Steel cans are too strong to crush like that. Aluminium cans weren't introduced until approximately 1965, although the movie was set in 1962. http://www.cancentral.com/brochure/historyTimeline_f.htm.
Factual error: At the end of the movie when the riot is taking place, Niedermeyer takes out a bullet and fires upon Flounder from maybe ten feet away and misses - all the bullet does is shatter the seltzer bottle and nothing else. Whether Niedermeyer meant to miss Flounder or not, the bullet would have shattered the bottle with little or no deformation to the bullet itself and would have hit the pedestrian running behind Flounder.
Factual error: In the scene with the disciplinary meeting, the chalkboard says "Pan-Hellenic Disciplinary Council." National Pan-Hellenic Council is the governing body for sororities, not fraternities. Fraternity disciplinary hearings would be handled by either the Inter-Fraternity Council (IFC), or the school's Office of Student Conduct, in conjunction with the Director of Greek Affairs. Further to this error is that the rest of the chalkboard writing pertains to the meeting being held at that time, and Greg Marmalard calls the meeting of the "Disciplinary Council" to order.