Continuity mistake: When Trevor and Lucky go up to the rooftop before the final battle, they lean over and rest their hands on the middle of a tile. From the opposite angle, they're resting on the section dividing two tiles.
Continuity mistake: When Stantz finds the trash bag on the lion statue, the tip of the bag and the knot hang way over the edge of the base. An instant cut later, they are several centimetres behind.
Continuity mistake: When Trevor sticks his finger out of the leaking hole, there's black mould stuck to it, which disappears a shot later.
Continuity mistake: When Manhattan starts to freeze, the car speeds through the streets with Callie and Phoebe in the copilot's seat. In the close-ups, one can see that the place is empty. In some shots, there's a shadow of a bulky object, maybe a dummy of some sort or the driver, but it's definitely not the two actors.
Continuity mistake: The name tag on Podcast's uniform is always hand-written. When he puts on the scarf to start the final battle, it still is hand-written. When he shows up to smash the cables box, it's now a black and red sewn name, just like the rest of the Ghostbusters' uniforms. According to Ghostbusters Fandom there's a deleted scene where Ray gives Podcast an official name patch. (https://ghostbusters.fandom.com/wiki/Ghostbusters:_Frozen_Empire_Deleted_Scenes#google_vignette).
Continuity mistake: When the movie begins, the Ectomobile drives by Cole Haan and continues to speed through Manhattan. When the manhole flies upwards, the car is suddenly next to Cole Haan again. This also happens with other locations that the car drives by twice.
Revealing mistake: When Gary is being interviewed at the end, Slimer and the Dragon fly over them and away. However, Gary keeps staring at the entrance door; seemingly, the cue didn't work here. A shot later, from a different angle, he is suddenly looking ahead.
Continuity mistake: When the possessor moves the tricycle down the street to the Ghostbusters HQs, the doors get blown off the entrance, and the Ghostbusters log/sign falls to the ground (seemed like a soft landing, in that it didn't seem to shatter... but when the long shot of the ice/frost proceeding to the firehouse (Ghostbusters HQ) is shown, the fallen signage is nowhere to be seen. (01:29:38 - 01:32:11)
