The premise finds absent-minded chemist Grant, on the search for an anti-aging elixir, accidentally imbibing a concoction mixed by his lab chimp, setting into motion a series of predictable but effective age-regression routines between the scientist and his wife, who has also taken the potion. The script - by Ben Hecht, Charles Lederer and I.A.L. Diamond - builds to a strong pace midway, but runs out of steam toward the end, with the zaniness feeling a little tired, and having tapped out the potential of the age-regression gimmick. Hawks' direction is typically assured and seamless. He interjects a cute, interesting moment during the opening titles, admonishing Cary Grant ("Not yet, Cary!") for entering the film before the credits have ended, which has a self-reflexive, almost Tashlinesque quality to it.
Grant is clearly having a ball playing the uptight professor who sporadically morphs into a rambunctious adolescent and a naughty little boy in equal measure. Rogers again demonstrates what a fine and natural talent she had for comedy. Her interpretations of her various youthful incarnations are expertly played -- the highlight being an overnight trip to the couples' old bridal suite where they spent their honeymoon, with Rogers regressing into a reluctant bride on her wedding night, alternating between crying and quarreling with her bewildered husband.
It never quite builds to the inspired manic level of Hawks' finest comedies, but its best moments are still delightfully funny.