The character Shu Kai Kim is based on Korean-American Chol Soo Lee, who was imprisoned for nearly 10 years after wrongful conviction for a murder he did not commit.
When showing the original murder in flashbacks, the killer is standing five feet or more away from the body when he shoots him. When Dennehy tells Dodd and the flashback is shown beneath the bridge, the gun is aimed only a few inches from the previous bullet hole. A gun fired that close would leave burn marks and gunpowder residue on the victim's head, which would be incongruous with the eyewitness accounts of the actual murder.
During the prison knife fight, Kim stabs the Nazi in the chest. The knife then alternates between still being in the Nazi's chest to being (correctly) taped to Kim's hand.