1. The magnet can get stuck inside a box if it comes on the crate's respawn tile a while before the box respawns. The first time, I could do nothing but restart. I reproduced the bug right before writing this and now the crate is gone and does not respawn. This time, it was harder to get stuck.
2. Those mine-like exploding things might act weirdly. When I played before, some of them could be attracted without explosion if the magnet was right next to them. After repeling, they started to fall below the floor and teleporting back up, causing an explosion when magnet went on that tile. This time, they acted almost normally except I've managed to repel them before explosion and the explosion occured but didn't reset the level. Both times, I did it at the start of level 11.
I'm actually not sure if it is something wrong with the game or my browser.