What I Loved
Despite the action being (purposefully) repetitive, you built the tension incredibly well. It was visceral and strong. Have you read anything by Daniil Kharms? If so, this is very reminiscent of his work and if not I recommend reading "Today I Wrote Nothing."
I've wanted to do something in this vein and I am indubitably impressed by your treatment of it!
What I'd Love To See
Some of the action lines are a bit verbose. I think you could really jack up the tension by cutting those descriptions to the bone.
Sal's dialogue is a bit confusing in that he occasionally talks about never seeing Roger before which (even in this Universe) feels off. Since we see Sal as the "rational actor" in this exchange, I think you could plop something else in or just remove that dialogue. Perhaps "who do you think I am?" or even having Roger just cut him off.
Minor things all around, a testament to my enjoyment of the screenplay :)