Near the end of the film when Danny (as Tony) takes the knife from the side table, walks to a dresser and gets lipstick, then writes 'redrum' on a door. When Danny picks up the lipstick, the cap has already been removed and the lipstick pushed out (usually done by a turn of the tube). With the tension of previous scenes it is highly unlikely Wendy (assuming it is her makeup) would have put on lipstick before laying down for a nap then forgotten to put the cap back on. Also, the action is all in real time so Danny would have had to open and turn the lipstick on his way to get the knife, then return to the lipstick. This seems illogical. More likely Kubrick opened and pre-turned the lipstick for Danny, a young actor with only one free hand.