At the beginning of this episode, Screech was wearing Pink Panther slippers, but later when he was waiting in line for the concert, he was wearing red high tops.
Lisa is able to determine exactly how much money is in the bag ($5,000) without counting it. Remember during her birthday she would shake presents and know what was in the box, it's her running gag for the show.
The gang goes to a mall to buy U2 concert tickets, but concert tickets are mostly sold at the venue the concert is being held at, or else at the ticket vendor location neither of which would be likely to be in a shopping mall.
No TV show would leave $5,000 of money unguarded where anyone could steal it which would spoil the show and leave them out the money.
The two gangsters talk about their plan in character even though there are no cameras from the hidden camera show anywhere near them to film them talking in character.
The teenagers could not consent to be on the show without their parents' permission so why did the TV show choose to film them?