This is to answer your question in Reply #380 of the Danshi Koukousei no Nichijou thread as I think it is better to answer through a PM.
By "last Ep's Hero skit" I refer to the skit High School Boys and the Biography of a Hero in Episode 5; and the error is at approximately 15:44 of the said episode. The nature of the error was identical to what I said in Reply #372, i.e. wrongly referring numbered schools as grades.
Sage's translation at that point was:
[Rubber Shooter]'s the guy who beat up the fourth grade Matsushi brothers, and that first grader, Tabuchi!
The correct way to say it is:
[Rubber Shooter]'s the guy who beat up the Matsushi brothers from P.S. 004, and Tabuchi from P.S. 001!
Similarly, 23:37-39 of episode where Sage translated as
Back then, it took all the famous kids from the 1st up through 4th grade to take her down.
should have been translated as
Back then, it took all the famous kids from P.S. 001 up to P.S. 004 to take her down.
(Emphasis added for all quotes. I know most U.S. cities don't give numbers to their public schools, but this is the norm in NYC.)