When Johnny gives his cousin his jacket at the last dance, you see his cousin put the record on which they dance to. But, after they have finished dancing and the audience is all dancing, you see Tito conducting the music and the band playing the song!!
Max Clearly states .. (quote)'You have SHAPE music on this stuff?' So it is a record, but Titto is conducting shape music! it's not the band playing the whole song!
ACTUALLY, Max clearly says "You have SHEET music on this stuff?" Which convinces me that Tito is actually conducting the band, hance proving the slip-up!!
Actually its both!! They dance to the record and then the band start playing the music of the record!! the guy asks "you have SHEET music on this stuff?" because the song is pop music not commonly played by that type of band! This isn't a slip up, its the band carrying on from the record so that everyone can keep dancing!