Keith Gordon (who plays the kid they "kidnap") started as an actor in movies like the Stephen King classic "Christine", but is largely recognized now as a director. Some of his films include the fantastic 1988 political drama "The Chocolate War" (with Wierd Science's Illan-Mitchell Smith) and 1991 military drama called "A Midnight Clear" (with Ethan Hawke).
John Murice Jackson, best known for playing Rear Admiral A. J. Chegwidden on the CBS series JAG.
He also played an abusive male father figure. While Billie Jean is sitting in their car some young boys come up and ask if she is Billie Jean and can she help save their friend. One of the last adult males she had to deal with before the wrap up of the movie.
In the movie they have several scenes where the radio is on C-101. That is a real radio station there, one of the oldest to Corpus, we still have it and the dj in the movie, was I believe, one of the real djs on that station at the time.
Peter Coyote, the sympathetic policeman who pursues Billie Jean also played the mysterious government character simply called "Keys" (bc that's all we see of him) who pursues E.T. at the beginning in the forest.