When Babs Bryant leaves the flat, heading for Carter's car, her suitcases are red: but when she reaches the car, one is brown and the other blue. By the time their journey ends and she is shown into the country house, they are back to being red again.
A telephone should make a ringing sound to the caller even if no telephone device is connected on the receiving end. The ring sound sent to the caller is generated by the telephone central office.
After being shot and presumably killed, one of the victims is laying in a chair, obviously breathing.