Continuity mistake: When Molly takes Mikey to the Chubby Charles office to meet Albert, she changes his poopy diaper and slams it down on his new desk, rendering it junk. She then puts Mikey back on the floor, but never snaps the legs on his overalls. In the next shot, you see Mikey smashing Skeletor on the floor and his snaps are done, but when Molly picks him up to leave the office, they are undone again.
Revealing mistake: When Molly's mother is listening (to what she thinks is sex) outside the apartment door, the handle is shown on the right side of the door. But anytime after that the door opens from the left side. Both doors open on the left. (For some reason Molly has 2 front doors to her apartment).
Continuity mistake: After Mollie was called by the elderly housing unit's administration, in the scene that she is cleaning up Grandpa's mouth, she is using a piece of a cotton roll and its package, which is cylindrical, is on the table. After a few shots, Mollie is still cleaning up Grandpa's mouth, but with a tissue, and the tissue's package, which is rectangular, is on the table too.
Continuity mistake: While Mollie is hitting James with the broom, a box of Cheerios falls off the shelf and gets wedged between the shelf and wall. Soon after they sit down the box of Cheerios is not there anymore, nor is it on the floor. Also, a white knick-knack on the shelf is now on its side and books that were not there before have appeared.
Continuity mistake: When John Travolta puts Kirstie Alley in bed and takes the baby in the cab for a ride. The baby tells him to take the bottle with him. He takes it and places it on top of the baby, in the next shot when he is going down the stairs to the cab, the bottle is no longer there.
Plot hole: James and Albert have a fight in Molly's kitchen, then James throws Albert out the door. Molly then comes home and James inquires "Who's Albert?" Only problem here is in the whole previous scene between the two men, Albert never revealed his name to James, only as "Mikey's father" and "the kid's father." How did James know his name was Albert?