After Arlen puts the 45 record on, he jostles the stereo when he has his first back spasm. The needle clearly bounces off of the record but the music continues playing. After he falls to the floor, a close up of the record still playing is shown.
When Arlen first tries to sell books to the bookstore he is taking a different number to or from the cart or counter each time the camera leaves and returns to his character (takes two but has three and visa versa).
Arlen Faber: You wanna know something cool about shaking hands with little people? They see us shaking hands but they don't know that we squeeze the other person's hand so they - y'know - they just hold hands with you for a couple of seconds.