You can run through one of the twin lasers in BCZ1

[Majro]

One of the twin lasers after the spike wall that Metal Sonic breaks can be run through for some reason as seen in the attachment.
You can't stand in it and running into the other laser hurts you as it should.

Looks like this bug's been present in 2.1 as well,

Spoiler

 

[Sparkette]

I played that level earlier today, and deliberately ran straight through there without paying attention to the barrier, as I remembered reading this bug report. I hadn't noticed until now that they both travel the full height, and that the working one can appear at the bottom as well. Ouch.