The main title editing team put Morse code into the sound mix that says "please turn off your cell phones."
The town of "Stony Creek" in Nevada is a reference to the original movie. It was partially filmed in "Stoney Creek" in Ontario, Canada, about 40 miles from Toronto.
The number of Jack's taxi is 1975, shown at the rear right bumper. This is the year Escape to Witch Mountain (1975) was released.
"Siphon," the alien assassin tracking the children and Jack, is referred to as "Duranian series." Mr. Duranian was the secondary villain in Escape to Witch Mountain (1975).
According to several Disney fans theory pages, Anthony and Tina are Tony and Tia who returned to earth, sometime after the events of Return from Witch Mountain (1978), to assist wayward space travelers who inadvertently ended up on Earth. And as for why they didn't use their powers, is because they didn't want to risk blowing their cover with so many feds running around.
Ike Eisenmann, Kim Richards: The actors who played Tony and Tia in Escape to Witch Mountain (1975) and Return from Witch Mountain (1978) appear together in the same scene. Eisenmann is "Sheriff Antony" in the bar, and Richards is "Tina" the waitress.