Plot hole: It seems that after committing 6-odd counts of aiding and abetting, literally right in front of the strict Police Captain father of one of them, Ted and for that matter Bill, would be lucky to only go to military school, regardless of passing or failing one particular class.
Suggested correction: The threat of Ted having to go to the military academy in Alaska was because he was going to fail. Since they passed and graduated, there's no need to attend the military academy. Some time passes before Rufus brings the babes to Bill and Ted, so we don't know what punishment they were given.
This isn't ordinary misbehavior, it is a felony, what do you think the punishment would be? No TV for a week?
I don't have to speculate what their punishment would be. Certainly neither would be sent to military school (which is a TV and movie trope that wayward children get sent there anyways). Your mistake entry is not a plot hole plain and simple.
