In the middle of the episode you can see Sonny Barger's real first mugshot on the wall with the other club mugshots, Sonny Barger plays Lenny "The Pimp" Janowitz and is a longtime and most well known member of the Hells Angels Motorcycle Club and founder of the Oakland chapter of the Hells Angels.
At least twice in this episode, a stand in for Ron Perlman can be seen. When Clay and Jax arrive at the very beginning, it's not Perlman riding the motorcycle, and when the club enters the house of the mexicans, it's not Perlman running in with his gun drawn.
One of the men shot to death is laying next to a motorcycle. The position of both his legs & arms change. At 5:27 in his legs are pretty far apart & his left arm is leaning against the motorcycle while his right arm is laying by his head, elbow bent. At 5:35 in his legs are closer together, left arm resting on his left leg while his right arm is now laying extended straight out away from his body.