I think that the only thing you can do is water vigorously and often, without drowning the plants. If you were using a salt shaker to put down the salt, there is probably little to no damage; if you used the whole container and the little metal spout, that is a different story, and it depends on how much salt came out, and you, being already concerned about this, will envision pounds of salt. I don't think it's going to be that bad.

DO NOT FERTILIZE THE PLANTS ON TOP OF THIS - baby them, give them mulch, and watch them, but don't give them something else to try to take in. Just water.

Before you beat yourself black and blue, remember all the tons of road salt that wash ff the roads during and after the winter - yet most things survive just fine.

How much salt over how many square feet? Approximately.

Don't repeat but unless it was pounds and pounds, I doubt it will be so bad. It will also depend on your soil and how well it tends to drain out and down.

Invest in some slug bait :-) Sluggo is a popular brand and is considered ecologically safe.

Ahh. I remember going out at night into my dads garden with my brother carrying flashlights and salting slugs. ... good times.

Now go get the iron based bait like gardengal says and have some fun.