In The Real Ghostbusters, the movie Ghostbusters exists as a retelling of their story (they even mention the names of Dan Aykroyd, Bill Murray, Harold Ramis, and Ernie Hudson). Does this mean that the movie canon is fiction and the Real Ghostbusters are the true stories of the Ghostbusters?
https://officialfan.proboards.com/thread/626995/real-ghostbusters-true-canon?page=1
That is how they tied it into the movie for that episode you mentioned called Take Two. They also tied it into the continuity of the first film with the episode Citizen Ghost. They also reference the first film in the episode The Revenge of Murray the Mantis. I don't like season 3 and on with how they changed the show but a later episode Partners in Slime also ties into Ghostbusters 2 as well.
Personally I only like watching the first 2 seasons (with the exception of Ghosts R Us, Kiler Watt, Troll Bridge, and Banshee Bake a Cherry Pie)