Not sure if you're still looking for more pointless things, but discovering this thread I had to add to it.

A Surface (flooring) that just looks like the ground (sand maybe? so you're even slower?) and behaves the same way.

Power poles that can't connect to each other or anything else.

Inserters ...

Woo! Finally a use for all my wood in endgame I keep having bots dig up!

Having played other games with this functionality I still catch myself doing it, especially with rails, go past the one I want and try to go back.
Assemblers using liquids where you want the output on the left... >_<