Continuity mistake: Steve's hair is soaking wet when Francine jumps in the pool, yet dry as a bone when Francine emerges from the pool moments later. (00:03:45)
Continuity mistake: When Francine brings lemonade on a tray for Steve and his friends, she assumes Snot is drowning. Francine then drops the tray and it lands on the ground before jumping in the pool after him. The tray disappears when she emerges from the pool with Snot. (00:03:45)
Chosen answer: It is just the decision of the creators to do so.
MasterOfAll