Just a couple of add-ons.
1) As mallard states, flushing with lots of water will probably get rid of the excess acid, but you are better off making a solution of water and baking soda and keep applying until you no longer see any reaction (bubbles). Flush again with your baking soda and then flush heavily with water.
2) Don't let it touch anything aluminum unless you really want to get rid of the aluminum.
3) If you are diluting the muriatic acid ALWAYS add the acid to a volume of water. NEVER water to acid. The reason is that water and acid combine in an exothermic (heat generating) reaction. If you add a little water to acid, the water heats up and boils almost immediately, splattering acid all over the place.
