Possible Spoiler...

What do doorknobs look like in that world?

That was one of the worst things in the movie. If you're going to posit a world with sausage fingers, then everything would have to be different in that world simply because of the absence of fingers. Like the way clothing works, the way pianos are designed, and so on, but no, they just kept everything the same as in our world. That's called not taking your own work seriously, and another reason I gave this movie a 5.