Continuity mistake: The chocolate stain on the baby's face when home behind the net changes from dark to light between shots.
Continuity mistake: When Wayne walks over to the playpen, the baby is sideways, fidgeting with stuff. An instant cut later, he is facing Wayne, and his hands are in a totally different position. And yet, an instant cut later, the baby is touching Wayne's helmet.
Continuity mistake: Nick and Wayne walk towards the giant baby for the first time, next to where a clock is. In the wide shot following, they're two metres behind, walking towards that same spot.
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: 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.
Continuity mistake: After he eats the entire box of fudge bars, Adam has chocolate smeared all over his face. The smudges change shape and intensity several times between takes. (00:39:00)
Answer: She may have said goodbye to Adam but it just wasn't shown.