When Dracula goes to the building where the therapy group meets to find Renfield, it is night time. But when Dracula walks around the room talking to Renfield, the windows high up on the walls behind him clearly show it is daytime.
In the fight in the restaurant Teddy gets stabbed in the neck with a fork later on though there's no evidence of this no bandage or plaster nothing.
Towards the end, during the "final battle" sequence, Renfield's sweatshirt suddenly shows 4 bullet holes. As he isn't shot during this sequence, this is clearly from an earlier deleted scene.
Renfield uses what appears to be either Chloroform or Ether on his victims, knocking several out within seconds. In reality both anesthetics take 15-20 minutes to render unconsciousness and since they evaporate very quickly need to be constantly freshened using a drip process that keeps the mask saturated at all times.
When Renfield splits the thug in half on the railing, you can see afterwards he's back in one piece.