Continuity mistake: When the family arrives home from the bowling alley, it is dark and pouring rain. After the kids go to bed, Carl and Harriet go to the kitchen and talk. If you look out the windows, it's daylight.
Carl, Eddie, and Steve are out ice fishing. At one point Carl falls through the "ice" and you can clearly see that the "ice" is made of some sort of styrofoam. It looks like the stuff used for packaging. The snow looks just as fake.