Fatty & George (1981)

Fatty and his sister George are the children of a scientist who is experimenting with time travel. There is an accident with the time travel experiment, leaving their father trapped in another dimension. Meanwhile, criminals are after the crystal rod that is an important part of the experiment. The crystal rod is able to freeze time around the bearer of the rod. With the help of their friend Izzy, aunt Kath and grand father Bert, Fatty and George search for a way to bring their father back, while trying to outwit the criminals. Added to this, other teenagers after also after Fatty and George.