A character is hit with a hammer in the basement. The killer quite clearly swings upward with the hammer, striking the other character under the chin. In close up, the victim has a large hammer-shaped wound over their right eye socket.
Around the 38 minute mark, the barkeeper drinks from a clear glass. In the next shot,he is seen drinking from an embossed glass.
Around the 45 minute mark, Don is on the phone to Liz on a video call. He's clearly using the rear phone camera as he's showing her the freshly-decorated wall and smoothing it down, yet she sees Sarah walk across the room behind him, implying use of the front phone camera on the call.
At the 44:14 mark when Don is texting Milo he holds up his phone and the times of the messages are 3:43am-3:47am although clearly days apart.