[4] A young writer, Cassandra, struggles to write a eulogy for her late mother, Elaine, who gave up her career to raise her children.

The site's critical consensus reads, "Mouthpiece interrogates gender norms with wit and ingenuity, portraying its main character's inner conflict through a pair of separate performances.

"[6] Glenn Sumi of Now gave the film a 4/5 rating, writing, "[Patricia] Rozema's version of Amy Nostbakken and Norah Sadava's award-winning stage play does more than just open the work up; it fills in key bits of information, shows us Cassandra out and about in Toronto and gives everything an affecting emotional resonance.

"[7] Scott Tobias of Variety called it "a thoughtful interrogation of modern womanhood, leavened by gallows humor.

"[8] Pamela Hutchinson of Sight & Sound wrote: "While the script's cleverness and wordplay betray its stage origins, it's bracingly sharp, and explicitly a feminist text.