As a Preamble DO NOT DO THIS. If you find a bug, do remember to undo the damage and report responsibly..
I just had to edit a post(now deleted) that horribly broke the sandbox. I had to figure out how to fix this, and a workaround for people with mod and editing powers is to replace the markdown with a placeholder that's not broken, once you find the edit button. If things are completely irrecoverably broken, if you can find the post ID, you can also do the/posts/post_id/edit route.
Now, amongst other things, it ruins the page controls
(If any other mods come across this, that edit link works and you can edit then delete... )
And the rest of the question
it also breaks the revisions page for that revision slightly
I mean, it breaks the edit page slightly too
Also seems to break the footer where the triggering content exists
Posted for documentation purposes, and status reviewed and deleted the post that triggered it so no one gets ideas. :)