Continuity mistake: At the end when Gilbert is giving his "I'm a nerd" speech, he finishes and there is a pause. You can see Lewis' shadow coming to Gilbert's side from screen right before he actually comes over.
Continuity mistake: During the sequence with the football players and liquid heat, some of them end up on the ground in pain. In the next shot from the opposite angle, none are on the ground.
Chosen answer: It's the song "Daisy Bell" by Harry Dacre.
Grumpy Scot