After having had sex with Brooke Morrison, Tim Whalen has a sweat-wet back and in the next shot is dry.
During a struggle for a gun between Tony Gateworth (John Glover and Tim Whalen (Rob Lowe), they end up with Tony against a wall when the gun goes off. He slides down leaving a smear of blood from where his head was but there's no sign of a head wound and when the gun went off their hands were down at waist level.
The gun in the death scene is an automatic pistol. After it is fired it ends up on the floor, where it is shown with the hammer not cocked. A semiautomatic pistol such as that one recocks itself after a shot is fired. The hammer should have been cocked.