When Turk and Carla are subduing Irv the security guard, Carla jabs him with a syringe - presumably a sedative. However, she never pushes the plunger on the syringe but Irv passes out anyway, without actually being injected with anything.
In the scene when the band is playing at the end, a trombone slide is visible with the slide upside down. This is obvious by the spit valve being on top instead of on the bottom of the slide.