She has appeared in films such as Men in Black, Forrest Gump, The Negotiator, Holes, Daddy Day Care, Going in Style, and The House That Jack Built.

[3][4][5] She graduated from Le Moyne College in 1983 and then two years later, she earned her Masters in Fine Arts from The Catholic University of America in Washington, D.C.[6] She made her television debut in an episode of The Golden Girls in 1990.

In 2000, she shared the screen with Björk in Dancer in the Dark by Lars von Trier, as a sympathetic jail guard.

In 2021, Fallon wrote and starred in Rushed,[9] co-produced by Lars von Trier's Zentropa Entertainment, and featuring Ellen Cleghorne.

[10] Also starring Robert Patrick, Jake Weary and Peri Gilpin, Vertical Entertainment has acquired the distribution rights.