Amazing Planet: Mystery Quest (1998)

In this movie, the aliens and Orb take a look at the mysteries of Earth, including the sudden disappearance of the Mayan civilization. The aliens think that the mysteries were caused by their arch rivals the Argoonians but the mysteries were not caused by the Argoonians. At the end of the movie, Kidogo informs Rip that they are about to enter another one of Earth's mysteries: The Bermuda Triangle. Orb tells Rip and Squeege that many planes and ships disappeared without a trace upon entering the triangle. Rip thinks that what Orb was telling them is nonsense and tells Squeege to fly the ship into the triangle. Suddenly the ship (with Rip, Squeege, Kidogo and Orb inside) disappeared. The movie ends with a sign saying To Be Continued. - on the screen.