Myth #35 - If a fielder catches a fly ball and then falls over the fence it is a home run
As long as the fielder is not touching the ground in dead ball territory when he/she catches the ball, it is a legal catch if he/she holds onto the ball and meets the definition of a catch. If the catch is not the third out and the fielder falls down in dead ball territory after catching the ball, all runners are awarded one base. If the fielder remains on his feet in dead ball territory after the catch, the ball is live and he/she may make a play.
LL Playing Rules: 2.00 CATCH, 5.10(f) & Note, 6.05(a), 7.04(b)