Les Gropp and Williams were both transported to the hospital via helicopter and Tol Gropp and Arhets rode to the hospital with EMTs.
Les Gropp had 13 metal plates installed throughout his face, but is doing well. Williams suffered a concussion and Arhets and Tol Gropp had minor cuts and bruises.
The National Transportation Safety Board is investigating the crash and has the plane secured in a storage facility for further examination, the agency said in a preliminary report.
"Loss of control happens because of some pilot error," said Earl Weener, an NTSB board member. "You let the airplane get too slow and you've got the wrong configuration or you haven't got the capability and performance that you need."
The passengers believe the plane experienced a downdraft, a dangerous, vertical movement of air caused by the weather.
Arhets said the men are all amazed to be alive and grateful for all the help they received. He is at Disney World, fully aware of how close he came to missing the celebration.
"I'm ecstatic to be here," he said. "Life takes on a whole new meaning."