Continuity mistake: Just before Sport and Jeb come back from their first visit with Aunt T, their parents are walking around the pool deck where it's fairly dry. But when the children come back, the area where they are helped out of the pool is suddenly very wet, probably from earlier takes. (00:13:40)
Continuity mistake: When Sport and Jab jump into the pool for last time, Sport is seen wearing a shirt. But,when she comes out at Aunt T's house she is wearing a swimsuit.
Answer: It's explained in the episode. The aliens are experimenting to see how humans react to various scenarios. This just happens to involve them using super strength.
Thanks. It's been a long time since I saw the episode so I forgot.