Dead Man's Shoes (2004)
Still photo on wall in Sonny's house.
A poster for Enter The Dragon is on the wall at Sonny's house.
Richard's army jacket is identical to Travis'. Also, similar themes throughout (disillusioned army vet) and a Taxi Driver poster appears in Sonny's house.
Sonny has a Scarface poster in his house.
The acid trip sequence is heavily inspired by Natural Born Killers.