Trivia: Most of the names on the check-out card in the book are actual fictional characters or real people, most being pirates. There's Davey Jones, Bluebeard, Blackbeard, Captain Kidd, and Frank Beard. Frank Beard is a member of ZZ Top and incidentally the only member without a beard. (00:03:35)
Trivia: The two surfer dudes eating Krabby Patties after Spongebob and his friends appear, are Lloyd Ahlquist and Peter Shukoff, the creators of the internet series "Epic Rap Battles of History." They were also the writers and performers of the rap battle before the credits.
Trivia: The two popsicle sisters holding hands are a reference to "The Shining"
Trivia: The baby in the stroller that said "SpongeBob" is voiced by Stephen Hillenburg, the creator of SpongeBob.
Answer: The first movie is actually set after the series finale of the show. This is because Stephen Hillenburg wanted the show to end at the Season 3 finale and for the first movie to conclude the series, but Nickelodeon disapproved, since the show was making them heaps of money. So the second movie is probably in line with the episodes after Season 3 and before the series finale. So no, it is probably not a prequel. If we look at it from a logical point of view, Plankton could have been released or escaped, and the Krusty Krab 2 could've closed. We don't know how far apart the episodes and movies are set in terms of time. The series has lots of inconsistencies anyway.
MikeH