Ok, I don't want to get too overwhelmed in this, but I find it fascinating, so here's what I know:
I tried to recreate what happened using save states at the end. It didn't work. But, I guarantee it was something like this:
http://dehacked.2y.net/microstorage.php/info/1464479426/There%20is%20no%20spoon.fcm
I messed up, fell down. There are many sprites on the screen, so I'm thinking could it behave in the same manner as a screen scroll. (I'm just brainstorming here. Maybe somebody could run a bot to see if it's possible.)
Here's the original movie I made right after I noticed the wall on the left. It's not a speed run or anything, (I was rather shocked) but you can see I run back there after death and the same effect isn't seen. (I'm sure it's possible to hack this as well but it's all I have as far as validity is concerned.)
http://dehacked.2y.net/microstorage.php/info/452821165/WTF.fcm
edit: I'll try to re-create this also, I'm not sure it can be useful but who knows.