Factual error: In the scene where we first meet Rosie, it opens with a shot of the house and then goes inside, passing by some pictures of Rosie and her husband. One of them, a picture of their wedding, says "Frank and Rosie - Wedding 1948", but then when Rosie is talking about how her husband will know how much she still loves him after all those years, Robbie says that he hopes that he and Linda will be as happy as Rosie and her husband on their 50th anniversary. If they got married in 1948, they would be closer to their 40th wedding anniversary. Since the movie is supposed to take place in 1985, this would actually be their 37th wedding anniversary.
Continuity mistake: During the 50th wedding anniversary party, after Rosie is done singing, she walks over to her husband Frank and they embrace with her on the left, and him on the right. The camera cuts away to Adam Sandler, then back to them, only now Frank is on the left and Rosie is on the right. The camera cuts to Adam again, then back to the couple where they are in their original positions.