In the 1970s, Thomas Popper Jr. uses an amateur radio set to communicate with his father. It is operating around 21.2460 MHZ; however, during this time period, this was not an available voice frequency to American amateurs.
When Janie and Billy enter Mr.Popper's "snowy" home, Janie has the keys in her right and her left hand is in her coat's pocket. A few seconds later, she throws a snowball to her dad. But, in those seconds, she didn't bowed to take some snow for snowball.