Look for gaps between the walls and floor around the wet areas. Look for the floor sagging at the edges. Wall coverings delaminating. How about the possibility of plumbing leaks? Is the top seal of the slide making good contact?
If you're lucky the water might have just wicked across the floor on top of the plywood. Pull off some of the material under the trailer floor and see if its wet under there as well.
Don't know if its an issue where you live or not right now but can you get the trailer inside somewhere so it doesn't get rained on until you can find and seal the leaks? Get a couple of fans blowing on the wet areas of the floor, that will help speed drying.