I was watching a Showdown! match wherein a Salazzle with Corrosion was holding a Toxic Orb, and the user was baffled that his Salazzle didn't get TOX'd after Turn 1. I did some science in Ultra Moon and sure enough, a Pokemon with Corrosion will TOX itself with the Toxic Orb even if its typing would normally prevent it. Why you'd want to do this I don't know, but it is indeed a thing and it should probably be fixed in Showdown! proper.
Another thing I didn't see tested in Showdown! that happens in the main series is that Fling + Toxic Orb with Corrosion can TOX targets that are normally immune to it, so if that also hasn't been looked into then it probably should be.