Director Carl Reiner, most closely associated with the homey values of situation comedies, shocked, surprised, and (in some cases) delighted his admirers with the jet-black comedy Where's Poppa?. George Segal plays Gordon Hocheiser, a New York attorney whose love life is constantly being sabotaged by his senile mother (Ruth Gordon), who constantly asks the question of the title. (She doesn't realize Poppa is dead). Every time Gordon has a prospective bride or lover lined up, Mrs. Hocheiser gums up the works with her insane behavior. The attorney at last finds a kindred spirit in the beautiful caregiver Louise Callan (Trish VanDevere), who has likewise been a victim of someone else's eccentricities (her first husband used the conjugal bed as his own personal toilet). When Mrs. Hocheiser chases Louise away like she has all the others, Gordon begins entertaining notions of killing his mother. In desperation, Gordon begs his brother Sidney (Ron Leibman) to take his mother off his hands, which leads to several comic vignettes in deliriously bad taste. The film's incest-themed original ending (trimmed from the video version but still included in cable prints) finds Gordon climbing into bed with Mrs. Hocheiser, only to be greeted with a "Here's Poppa." The celebrated "tush scene," wherein Mrs. Hocheiser bites Gordon on his bare backside while Louise looks on in horror, packed a real wallop back in the early '70s, as did a courtroom scene involving a disgruntled hippie (Rob Reiner) and a psychotic U.S. general who graphically describes his homicidal acts against the Vietnamese. Though Carl Reiner would continue to "push the envelope" in his later films (Steve Martin as a "poor black child"? George Burns as God?) he would never again attempt anything as risky as Where's Poppa?.
~ Hal Erickson, All Movie Guide