When McLeod takes Larca's head, you can clearly see McLeod is standing in the middle of a pyrotechnic setup shaped like the Moche God that was eventually lit up on the ground.
When Gabriel is with Derek in the morgue, he makes an erroneous allusion to Psalm 23 in the Bible. He says, "I have brought you safe through the shadows of the valley of death." The real quote is "valley of the shadow of death."