Deliberate mistake: In the pitch dark mansion dining room, the approaching zombie's screams are instantly interrupted by silence whenever the flame from Chris' lighter goes out, and then the screams instantly resume when the light returns. While this is obvious artistic license, for the record the level of darkness would have no bearing on whether we can hear the zombie screaming.
Deliberate mistake: When Kasady and his symbiote are fighting for control at the bell tower, they are reflected inside Venom's eyes...who is lying on his back in the middle of the cathedral and is nowhere near and at the totally wrong angle for a reflection like that to happen. (01:15:50)
Deliberate mistake: The doctor appears to write just three numbers or a short wavy line on the back of his business card for the phone number he told Marjorie to call (to get a second opinion about Nathan). (00:42:35)
Deliberate mistake: The Janitor was driving away from Willy's but the explosion shows up in the front of his sunglasses. (01:21:47)