Continuity mistake: When Adam is toying with the car in Las Vegas, the wide shot shows the girl's arms extended, but in the close-up they're covering her face. This swaps back and forth.
Continuity mistake: When Wayne is in the back of the van with his machine when the motorcycle cops are following him, the switches on the machine change position depending on the shot. At first, you see #2 and 5 in the up position, but then only #4 is. He flips them all up and the lights come on, but in the next shot, the lights are off and not all the switches are up. A similar thing happens when he unshrinks the cops.
Continuity mistake: In Las Vegas Adam slides the car and sparks come out. His brother is either holding the wheel or waving his arms, depending on the shot.
Continuity mistake: When Wayne is on top of the giant bunny holding the bullhorn he is in front of the bunny's hair in the close-ups, but hidden behind it in the angles where the baby holds the toy (though the bullhorn is still visible), obviously to hide the miniature-Wayne trick.
Continuity mistake: The chocolate stain on the baby's face when home behind the net changes from dark to light between shots.
Continuity mistake: Adam picks up the yellow car sideways but the shot inside shows Nick and Mandy upside down.
Continuity mistake: When Adam is blown up, he gets chocolate all over his cheeks. Then he has a nap, but when he wakes up, all the chocolate is gone.
Answer: She may have said goodbye to Adam but it just wasn't shown.