your pedals will try to fall off
This is an Urban myth. Try pedaling your bike forwards with a spanner on the spindle. If on the normal way they will unscrew.
If the bearings fail they are designed to unscrew rather than rip your foot off (more if you are wearing toe clips).
I ran my cranks on backwards for about 16 years. The pedals Im using now are the first pair for ages Ive not had to swap the spindles over on.