I'm sure if you haven't seen anything on the news by now, everything is fine. Stretchers and backboards are used at the waterparks on a (literally) daily basis. This is mostly a precautionary measure due to the possibility of a spinal injury. Back in my days at typhoon lagoon, it wasn't uncommon to call EMS twice or more a day during peak times, and two or three times a week in the off-season. Which brings me to an important reminder:
The Typhoonguy waterpark tip of the week:
It's best to read the warning signs at the entrances of attractions at waterparks. This is something most people skip in the theme parks, because they always say the same old thing. Arms and legs inside, no pregnant women, attraction uses fog, yadda yadda. However at waterparks there are some very IMPORTANT tips. Such as not sitting in the wave pool. Many times, people are not aware of how strong the waves can be, and when in the sitting position, you can be knocked back, hitting your head and causing the possibility of a cuncussion (sp?).
As far as leaving the wave pool, if there is an emergency procedure in the wave pool, lifeguards have the ability to clear it out if they feel it necessary. One of those 'better safe than sorry'.