Continuity mistake: When Henry is leaving the dock, Alexa waves with her right hand. Notice the watch. When Alexa grabs some butt from Doug, The watch is now on left arm. (01:23:10)
Continuity mistake: The dark roots of Lucy's hair can be seen off and on throughout the movie. One day she will have dark roots, and the next day she won't.
Continuity mistake: When Drew is in her car at the restaurant, chastising Adam Sandler for faking not knowing how to read, a truck with the "Spam" logo drives by. The DVD commentary states the logo was added digitally later. When Adam's character runs back to his car, the logo is not on the truck anymore. (00:37:10 - 00:38:20)
Continuity mistake: The waiter and Adam are talking about Lucy in the diner. There is a shot of Lucy across the diner. She is building a waffle house, and there is a glass of water to the left of her plate. Seconds later, the waitress walks by, and the glass is now a cup of coffee. (00:32:15)
Continuity mistake: Lucy's lemon wedge appears out of nowhere and disappears a couple of times before Henry even uses it. (00:11:45 - 00:13:20)
Continuity mistake: When Lucy watches the video tape for the first time, then goes outside and stands on the deck she turns to face Henry and her Dad. There are two small boats going toward each other just as they are about to pass the scene cuts back to Lucy, then you see the two about to pass each other again. This happens a total of three times.
Continuity mistake: Throughout Henry's "song," Lucy keeps changing how she holds the cup. (01:09:00 - 01:10:30)
Continuity mistake: When Lucy is telling Henry about her diary, her hair moves from behind her ear to covering her ear between shots.
Continuity mistake: When Lucy and Henry are talking on the parking lot (just after he pretended to be illiterate), a boat with purple sail appears out of nowhere behind Henry and then disappears. (00:37:45)
Continuity mistake: Following their first encounter at the restaurant, Henry and Lucy are walking through the parking lot. The lighting conditions change from sunny to overcast between shots.