When Setrakian shows Nora his tattoo, it is shown to be somewhere near his elbow. In all other episodes, it is further down his right forearm.
When Gus is training under Vaun's tutelage, he is told to fight a strigoi hand-to-hand. He pulls the vampire's stinger out of its body and drops it on the ground, at which point Vaun congratulates him on a job well done. However, when the camera goes back to Gus, the previously-intact proboscis has somehow been cut into two pieces, even though Gus had no bladed weapon and no audio indication was made that he cut it.
Captain Kowalski is mistakenly shown wearing a lieutenant's shield.