I know from personal experience that is possible to reverse the polarity on a compass needle, so that the "North" end points SOUTH.

Some years back, while playing with a magnet & my old Boy Scout version Silva Explorer compass (non-liquid filled), I managed to stroke the magnet down the long axis of the needle, which, as noted elsewhere, will magnetize an item. It reversed the polarity of the needle. After an "Ooops!", followed by a couple of minutes of "Gee, did that really happen?", I repeated the process & returned the polarity to normal.

Could this happen "in real life", i.e., in the field? Possibly--if the magnet happened to be beneath the compass, & the compass was moved by sliding off of the magnet, rather than picking straight up.

If 'twere me, I'd leave the magnet at home, or at least, not have it near the compass.

David