One trick I learned on The Black and the Blue website is what to do if someone accidentally uses a permanent marker on a slate. Just write over it with a true dry-erase marker; the solvent in that should loosen up the ink from the permanent marker, allowing you to erase it all. I haven't personally tried this (thankfully I haven't needed to), but the video on the website showed that it works.
It looks like the whole camera rig shook when he pulled on the tape, and in fact the final shot does shift a bit left and right at around halfway through the focus pull. I would imagine the average viewer would never notice it - I'm sure I wouldn't have either if I hadn't come across this article.
Lots of people seem to think they know exactly what the director was thinking and intending, especially ironic with interview-shy Kubrick. I watch a movie, see something interesting, and think of what it means to me, not the director. (And Kubrick is the director whose work most resonates with me. But I don't claim to know what he was thinking.)
I would imagine the light output for those would be really low compared to these floods. You could set up some lights, flag them off and then have someone wave strips of duvetyne that have been nailed to a small board in front of the lights.
I have to wonder, when it comes to subtle recurring motifs in a film like the roses here, how much of an effect it has on an audience's subconscious interpretation and their conscious entertainment satisfaction. I'm not suggesting things like this don't have an effect, I just honestly don't know. I've certainly never felt anything about a film that I could attribute to things like this, and I probably rarely ever really notice them.
There's a "does a bear shit in the woods" joke here somewhere, but I'm too tired to think of one. I'm relying on you all to step in and fill the void.