The first film, Adam, played on TV in 1983 for the first time. This sequel shows that Mr. & Mrs. Walsh are going to watch it at home alone. Yet their daughter in this sequel is at least 4 years old. Their daughter was not born until middle of 1982. She would only be a little over 1 year old when the first movie that they are portrayed as watching here came out.
At an hour in, when John Walsh is having coffee with his mom at the airport, he calls her "Gram" instead of "mom".