Corrected entry: Before the storm, the Professor said that his equipment and the radio hadn't worked for ten years, and after getting to Hawaii, they were confused by the procession of presidents. Yet, the radio, when it was working, would have kept them up to date on all of the events up to the tome that it stopped working. Even then, the professor could have repaired it.
Corrected entry: They've been stranded for 15 years. So this takes place during the mid-late 70s after Watergate. Yet the Howell's and MaryAnn are the only ones who haven't aged or changed their look a bit, while the others look appropriate for the time gap.
Correction: The actors did not go into suspended animation after the show ended. The show began in 1964. The movie was shown in 1978. All the actors are fourteen years older just like their characters. The fact that some of them aged better than others is definitely not a mistake.
Correction: The actors who played the Howells were in their 50s and 60s during the shows original run. Most people after 50 (or definitely 60) don't look too much different if they age 10-15 years. Mary Ann DID look a bit older but was still only 40 during this movie and Ginger was played by a different actress Judith Baldwin (who was younger than the original Ginger Tina Louise explaining that). Others were more middle-aged so you can tell the difference easier.
Correction: In ten years the presidency would have switched at least twice so no mistake there. Also, the professor did not have the ability to fix the radio since he didn't have proper tools.