During Sweet Johnny's last stunt Joy shoots 2 of the 3 balloons, but once everyone is on the ground 2 strings being held up by balloons can be seen.
Once Sweet Johnny and Earl crash to the ground a balloon can be seen, but the next shot shows no balloons.
Three weather balloons are much, much too small to even just lift a single person, let alone two grown men and a lawn chair.
When Sweet Johnny and Earl crash to the ground, it's clearly visible that they landed on a soft platform and not the hard ground.
Shelia says Johnny got hurt the summer Livin' la Vida Loca was big, but earlier it is said Johnny got injured 10 years ago which would be the year before the song was released.
Earl says that Johnny is the first person that he couldn't cross off his list. But in an earlier episode, he put Neglected Randy on his list, which he never planned on crossing off because he would never stop making up his neglection of Randy.