Avatar: The Way of Water is the weekend’s No. 1 movie again. But the movie—or at least the title—comes with a bit of a paradox. Because right now, the box office is anything but fluid.

The Way of Water claimed the weekend’s domestic box-office title for the fifth-straight weekend, collecting another $32.4 million to add to its overflowing treasure chests. James Cameron’s latest epic has now banked $564.2 million in North America, and a staggering $1.9 billion worldwide. Admittedly, that global mark is still about a billion behind the original Avatar (the No. 1 grossing film of all time), but still not too shabby.

The rest of the box office looks almost like a carbon copy of last week’s list. M3GAN finished second to The Way of Water for the second straight week, collecting...