I don’t know what’s crazier: The fact that “The Day the Earth Blew Up” is the first fully-animated “Looney Tunes” feature ever released in theaters, or that Warner Bros. — who first commissioned the project for HBO Max (Rip) before shopping it around to other buyers — was so determined to prevent the film from achieving its destiny.

Can a fun, slap-happy, and beautifully animated buddy comedy fronted by some of the most famous cartoon characters of all time and budgeted at 8.57% the cost of “Inside Out 2” really be that big of a risk? New distributor Ketchup Entertainment is certainly hoping to prove otherwise, and they’re doing so with the benefit of a movie that’s very much about the joy and importance of preserving the classics long after they’ve gone out of fashion.

A wise man once promised “that gum you like is going to come back in style,...