I don't know if you guys already know this. But it's not on the site... I don't think.
On 5-1 you jump on the first Koopa and kick the shell forward killing all the enimies in front of it. But you will only get the 1up if the Koopa shell is on the edge of the screen while killing the last few enimies. Yeh. I was bored and trying to find some secrets that no one ever found yet. Maybe this pointless trick could be it.
If it's already on there, my bad.