Fairly early recognisable break with this behavior:
- Console - map ge5map02
- Press J to skip the cutscene
- Run forward to the landing pad. Notice door on left of brick wall ahead of you. Run to it.
- Attempt to use the door
The door is a 3D floor controlled by a script, which when used makes it look just like a real door. Notice that you can run on top of the brick wall where the door would be. checkswitchrange was enabled in MAPINFO to stop people pressing use and activating the door when they're obviously not next to it in a three-dimensional sense.
Bump behavior works just fine, but this is a Doom map not a Quake map. The bump constantly retriggers if you keep walking in to it though, so you get spammed use sounds and console message about the door needing a yellow key.