According to Mckenna Grace, it was somewhat more difficult (at least for her) to work with the surviving original cast compared to Ghostbusters: Afterlife (2021) where the original actors came in late in the film and were only on set for 2 weeks to shoot the climax. In this installment, the original cast were on set for about 90% of the shoot. Grace admitted that while it was fun working with them and hearing their stories, she also felt a little intimidated and worried about screwing up in front of the guys who started this whole thing 40 years ago.
When Nadeem asks if anyone has a lighter, Ray replies that he stopped smoking in the 90s, whilst this may be a burden to their current predicament, it's a call back to Ray's bad habit, where he can be seen smoking throughout Ghostbusters (1984) and smoking a cigar in Ghostbusters II (1989).
The scenes in which Trevor attempts to catch Slimer are similar to a subplot that was filmed for Ghostbusters II (1989) but ended up being cut. In that deleted subplot, which also took place inside the Ghostbusters HQ and was supposed to be a running gag in that film, Louis Tully tried to catch Slimer on several occasions but failed. He also tried to bait him into a trap with food, something that Trevor does as well.
Was released 40 years after the original film (and 35 years after the first sequel). As a bonus, it will come in time for the 100th anniversary of Columbia Pictures and the 10th anniversary of Harold Ramis' passing.
Ghostbusters: Frozen Empire is dedicated to the late Ivan Reitman, the original director of the first two movies who passed away on February 12, 2022.