Continuity mistake: When the teachers play the confiscated tapes of Harry, it's Christian Slater's voice, not the disguised voice you hear on the students' radios.
Continuity mistake: The entire 'typical American High School' wears the same clothes two days in a row, as a result of one day in the script which was divided into two days during the editing process.
Continuity mistake: When the guy in suspenders sneaks a cassette tape of Harry's show into the boombox, at the place where the students are dancing, the recording of Harry busting Deever is a completely different performance. You can tell because the word "Why" (from "W-w-why is that, Mr. Deever?") is much lower in pitch.
Continuity mistake: When Mazzilli is talking to the reporter in front of the school, he lights smoking firecrackers and throws them behind him. When we see him light the first one, it is at least three or four inches long when we see it in his hand, but much shorter an instant later when it hits the ground. This happens again with the next one too, but this time it's shorter when we first see it and slightly longer when it hits the ground. (00:54:25)
Continuity mistake: When Paige is shown brushing her hair in front of the mirror, there is no background shown in the mirror behind her; it's completely black. We see this a few times while she's sitting at the dressing table, but then when she gets up to gather her things and take them to the kitchen, we see the room reflected normally. (00:43:25 - 00:44:30)
Continuity mistake: The FCC commissioner's limousine window goes up and down in between shots. (01:26:25 - 01:27:55)
Chosen answer: Well, with no actual scene where he confesses, it's left up to us to wonder. Personally, I find it unlikely that he'd actually admit the whole thing to his parents, but they're not stupid and already had their suspicions, so the lack of any great surprise on his father's part isn't unreasonable. You also have to remember that Mark's voice changer had already broken before they drove down to the crowd - his father would have easily recognised his voice before his actual arrival, giving him a certain amount of time to get through the initial shock.
Tailkinker