When Harriette brings Laura home from the party, the exterior of the house shows only the porch light is on, when they go inside, the living room lights are already on.
Laura's age is referenced as 16 years old, but she turned 15 three seasons earlier in 'Old and Alone'.
After Urkel hits the ball that bounces around the trees, the ball lands on the ground and disappears just before cutting to the next shot.