Apologies if this is already known, but I haven't seen it mentioned anywhere.

I was playing the game just now, and ended up making a mid-air jump that seems to be similar to SMB1's wall ejection jumps. This happened on a 1.1 cartridge (DMG-ML-AUS, though I doubt the region would matter) played with genuine/unmodified GBA SP hardware, and I don't have a recording (sorry).

The jump happened at this location on level 1-3: And followed a trajectory similar to:

I believe I collided with the side of the pipe at or around the second horizontal line, which may meet SMB1's criterion of hitting on a block boundary if the bug is actually the same. The only other thing I can think of that may somehow be related if it's not SMB1-like is that this pipe has a pirahna plant in it which iirc was heading downwards at the time - perhaps some collision with the edge of that?

As for what this means for the game... likely not much. Even if this can be replicated anywhere at will, so much of the game is already played at a full-run that the only potential saves might be not having to wait for a vertical platform in some spots and that's hardly significant considering the current time losses due to human error in even the best runs at the time of writing. So unless there's a way of wall-jumping off the screen and somehow breaking the game by doing so, at most this is probably just a few seconds off of the TAS time.

Still, I thought it was interesting enough to share with everyone.