Continuity mistake: When Michael's shown falling off the Wallace balcony in the opening scene it's on the front of the house not the back. Clearly this is a different house. (00:02:31)
Continuity mistake: At the beginning of the movie, the front door lights on the Doyle house are on, then off, then on again in just a few different shots.
Answer: There is a scene where Laurie dreams about meeting Michael as a young teen. It's unknown whether this is an actual memory of real events, but since nothing indicates otherwise, we could assume the he saw her at an older age when she looked closer to her 17-year-old self.