Continuity mistake: Right at the end, after Cassandra throws away the finger, there is the scene with her "family" finding the music box. Cutting back to her; she again has the finger resting on her shoulder/hair.
Philly Feast - S1-E3
Continuity mistake: Cooking steaks on the barbecue, one for him and one for the dog. On the barbecue, they are T-bones, but when he passes one of the steaks to the dog, it is a boneless cut. (00:37:00)
White Light - S2-E2
Continuity mistake: When citizen Z is searching for zombies, he approaches a door holding a pistol with an under-barrel attachment. When he goes through the door, the attachment has disappeared. (00:01:05)
White Light - S2-E2
Continuity mistake: Roberta is checking her magazine on the pistol and it's empty. In the next scene, without reloading, she fires 3 more bullets. (00:29:10)
Continuity mistake: When the lieutenant and the new guy that joined up in season 2 are in the hospital, he reaches for his gun, shoots, and...click. No ammo. The lady then pulls our her gun, slide fully retracted, finger not on the trigger and states "yeah, me too." Thing is - if the slide was already retracted from running out of ammo - wouldn't she already know? I mean, she holstered the pistol. More egregiously, every shot before this, her slide was not retracted, and the pistol was ready to fire, until now, when she suddenly has a retracted slide.
Continuity mistake: When Cassandra is chasing Addie in the woods you can see that she is not wearing her white boots but trainers or flat shoes. When she catches Addie the boots are back on.
The Siege of Murphytown - S3-E12
Continuity mistake: Towards the end a woman is walking towards the fence completely covered in blood and guts, we see close ups of her boots, trousers and hands all covered in dripping blood. In the next shot she is still walking but her boots and trousers are clean and the blood on her hands is very dry.