Continuity mistake: When at the end of the movie Kim Basinger sits with the Nice Guys (well, back-to-back with them, kinda), March is already wearing the sunglasses that he puts on when she says "Boys, boys." (01:47:15)
Continuity mistake: When the Nice Guys in the ending mention Lynda Carter, they are holding their smokes in entirely different ways between shot and reverse. (01:50:25)
Continuity mistake: Russell Crowe is dunked head and torso in a pool, immediately gives chase to Blueface, but he's basically dry when reaches Holly. Later in the movie it's even worse, since Ryan Gosling has a near-death experience falling in a pool, but he runs as normal, only slightly moist in the hair (and even pulls out a cigarette and lights it later by the time the cops arrive).