The film The Island of Dr. Moreau
(Marlon Brando, 1996) has one brief use of a paintball gun.
After Montgomery (Val Kilmer) finds out one of the creatures has
removed his implant, he tries to shoot him with what is presumably
supposed to be a tranquilizer dart gun. When fired, however, the sound effect is that of a small rifle discharge.
The gun is never seen clearly or up close, these were about the best
shots I could find. However, judging from certain features, like the
back-bottle air tank, and what appears to be a fixed feed neck, it is almost certainly a Tippmann 68 Special
fitted with a rifle scope.