Xkeeper | New SMB1 glitch with offscreen enemies @Xkeeper0 | Uploaded March 2009 | Updated October 2024, 17 hours ago.
Not that this has any use whatsoever unless you can hack a way to put enemies up there, but it can create a surprise when a Goomba suddenly falls out of the ceiling :)

I recorded this after I threw the enemy up there. Funny that I was trying to get a decent video of this repeatedly, and once I finally give up I do an excellent one and have to record it midway.