Scrat is the reason to see any “Ice Age” movie. Working like Wile E. Coyote, he gets into plenty of trouble just holding on to an acorn. When he’s not on screen, the film falls apart. Big time.

The last “Ice Age” film, “Collision Course,” opened in theaters in 2016, grossing $408.5 million globallly. It’s a franchise that’s had legs — the first film, “Ice Age,” bowed in ...