This mode allows you to play with most of the known bugs found in the original Lode Runner Online: The Mad Monks' Revenge. Quirks Mode is enabled by default but can be turned off.
You can download a puzzle set here that showcases these quirks.
Most of the bugs listed on this page are from Jason Summer's excellent Lode Runner fan site.
If you run off of a monk and onto a tile where there is an invisible exit ladder, you will "fly" until you reach a ladder or the edge of the puzzle. You can fly right through some kinds of blocks, but flying into others will kill you.
Found by Konstantin Seiler.
If you blow up a block directly beneath a ladder and then run over where it was, the block is treated as if it is still there. He won't cross over to the ladder. A workaround is to start to climb the ladder, then climb down. The same rule applies to a phase brick that is directly beneath a ladder.
Found by Howie Pelton
You won't drown if you climb down a ladder directly above liquid - you'll fall right through it! The same rule applies if there is a ladder on both sides of the liquid. Also, if your starting position is over liquid, you will fall safely through the first two tiles.
Found by Loyalle Chin and Jim Winkler
If you blast a hole two tiles above a monkey bar and three tiles above liquid, and then drop through it, you won't be able to grab onto the bar, and will fall to your doom.
Found by Jim Winkler
If you enter a teleport on the top row of the puzzle that has no other exits, you will get caught in an infinite loop.
Found by Jim Winkler.