The character of Tia in the flashback sequences was played by Kyle Richards, the real-life younger sister of Kim Richards.
Kim Richards (Tia) had a particular affection for Bruno the Bear. One day she asked to help bathe him and, acting uncharacteristically, the bear picked her up, swung and shook her vigorously before his handler finally got Bruno to set her down. Richards was terrified, but tried to play it off for the group of spectators which had gathered.
Kim Richards and Ike Eisenmann, who play the children in this movie and in Return from Witch Mountain (1978), appeared in a scene in Race to Witch Mountain (2009). Eisenmann is "Sheriff Antony" in the bar, and Richards is "Tina" the waitress. In this movie and its 1978 sequel, their names were similar: "Tony" and "Tia", respectively.
Bruno the Bear was only alert for about ten minutes a day, which the production crew had to carefully schedule with the children's two-hour work schedule.
Knowing that it was an integral part of the story, Ike Eisenmann (Tony) bought a harmonica and taught himself to play it, unaware that he would be dubbed in the end by professional harmonica player Tommy Morgan.