There is a gasket and a front crank seal. you have to pull of the pulleys and belts to change the cover.
If you replace the front crank seal the big bolt in the center of the crank pulley has to come off too, so you can remove the lower timing belt pulley....otherwise, you can just remove the 5 smaller bolts to remove just the pulley, then remove the timing cover.
The cover gasket is a foam like gasket (IDK if the new covers come with them, or if you reuse the old one)....it just seals the timing belt area to keep dirt and water out. The gasket has nothing at all to do with sealing the oil pan. Nothing should fall out, when you remove the timing cover.