I beat the level without any issue, version 0.55E. All of the doors worked fine for me.
I loved the idea of a fast food restaurant level, the cultists fit in perfectly in that setting and it's reminiscent of the Duke Nukem movie theater with the waist-high counters and trash cans everywhere. It's great!
True to the nature of the setting, I don't think I was ever in short supply of fast food to replenish my health, but ammo was a little scarce.
The discount suicide sign was pretty fun too. I wish there was more stuff like that although it would somewhat make the tutorial posters stand out more.
On that note, I do wish the graphics were more flashy in general, but I'm unsure as to how that would affect the overall aesthetic you are going for. Also, I was totally expecting interactive restaurant stuff like a grill that dispenses a hamburger pick-up, a deep fryer rack that goes up and down, etc. The secrets are pretty good though.
What's going on here? Actually, don't tell me.
I also found this one, do cultists sit on the toilet backwards? The mysteries continue piling on.