When Bautista and Quinn have to go retrieve Quinn's gun and phone, on the way back, there's a shot of Bautista from behind the driver's seat, and he has a blood spot above his holster strap on his right shoulder. In the very next scene, they are standing with the hood up on the side of the road, but the blood stain is gone.
It is possible to split a chain with an ax in a single blow, but not on a soft surface like a wooden table. The chain just gets pushed into the wood, and that absorbs too much of the blow's force. Th chain needs to be positioned on a hard metal surface.
When Dexter uses the ax to free Travis from the chains, he breaks the chain between the two shackles. When Travis stands up, somehow that has allowed him to remove the shackles from his wrists also.
When Dexter enters the church, he and Travis talk about Gellar, a crazy psychopathic killer, knowing full well that he could still in the church and can hear everything. Not very characteristic of either character.