glad the fish is ok jordan, definitely a close call...and definitely a good demo of how tough these fishes are. i have had my share of gars jump out for various reasons. if you have not done so already, i would tape down (along the corners) of the glass tops on your tank. this works well to keep cats (and other terrestrial creatures) out, and fishes (a big gar can eventually become strong enough to push open a typical glass top) inside.
another thing regarding the recovering gar; bump up your water changes for a week or so to stave off infection, but don't use melafix as it seems to create issues with oxygenation at the surface and water column in general. you may also want to put in a bubbler just to increase water movement (and therefore oxygenation) if the gar is still sticking to the bottom for the most part. good luck, and keep us posted!--
--solomon