Full Metal Jacket (1987)

Continuity mistake: When Gomer Pyle is in the toilet with his rifle and after shooting the drill instructor, Pyle sits down on the fourth toilet seat from the back of the room. In the next shot where Pyle kills himself, he is sitting on the third toilet seat. You can see this already from the front shot of Pyle when he kills himself because there is a rise in the wall next to the third seat, which is visible through the whole scene. It is more obvious in the following shot where you can see the row of toilet seats and Pyle sitting dead on the third one. (00:43:00 - 00:43:35)

Gunnery Sergeant Hartman: How tall are you private?
Private: Sir, five foot nine, sir!
Gunnery Sergeant Hartman: Five foot nine, I didn't know they stacked shit that high!

Trivia: Not really a mistake, given the need to maintain the story arc in the first half of the film, but in real life, Pyle would have been discharged from the Marine Corps within days of his starting basic training - for his own good. It happens all the time - dropout rate of boot camp recruits varies but is generally around 10%.

Question: Who's idea was it, or the reason, Kubrick decided to kill off Gunnery Sergeant Hartman? Was it to merely show the casualty of war?