KEVIN: This house is so full of people it makes me sick! When I grow up and get married, I'm living alone! Did you hear me? I'm living alone! I'm living alone!
Kevin gets his wish sooner than he expects…but he discovers that solitude isn't the bliss he expects it to be. Although he has freedom, he needs people to share his life with.
KATE: How could we do this? We forgot him.
PETER: We didn't forget him. We just miscounted.
KATE: What kind of mother am I?
FRANK: If it makes you feel any better, I forgot my reading glasses.
Uncle Frank takes forgetting Kevin pretty easily—he's laid-back about it. It shows that he's kind of a jerk, comparing a kid to a pair of reading glasses.
MEGAN: You're not at all worried that something might happen to Kevin?
BUZZ: No, for three reasons: A, I'm not that lucky. Two, we use smoke detectors and D, we live on the most boring street in the whole United States of America, where nothing even remotely dangerous will ever happen. Period.
Buzz acts like he doesn't care about Kevin...but maybe behind his idiotic justification for his lack of worry, there's a hint that he really does care, and he's just trying to cover it up? Maybe?
CHECKOUT WOMAN: Are you here all by yourself?
KEVIN: Ma'am, I'm eight years old. You think I would be here alone? I don't think so.
Kevin wants to hold onto his autonomy—he's not going to let his opportunity to live freely be spoiled by some checkout girl. Plus, Kevin thinks he made his family disappear—so he doesn't realize they're still out there looking for him.
CHECKOUT WOMAN: Where do you live?
KEVIN: I can't tell you that.
CHECKOUT WOMAN: Why not?
KEVIN: Because you're a stranger.
Kevin might mean this seriously—or he might just cleverly be keeping the lady off his case, so she doesn't disrupt his freedom.
KATE: Have you ever gone on vacation and left your child home?
GUS: No, no. But I did leave one at a funeral parlor once. Yeah, it was terrible too. I was all distraught and everything. The wife and I, we left the little tyke there in the funeral parlor all day. All day. You know, we went back at night, when we came to our senses, there he was. Apparently he was there all day with a corpse. Now, he was okay. You know, after six, seven weeks, he came around and started talking again. But he's okay. They get over it. Kids are resilient like that.
This is not a comforting story to tell Kevin's mom—now, she's worried that Kevin is going to be totally traumatized by the experience. And it compounds her feelings of guilt.