Actress Marlo Thomas has joined the cast of the Bubble Factory’s comedy drama “Two Goldsteins on Acid.”Thomas will play the mother of a pianist (Alicia Witt) whose life goes on a downward spiral. Other castmembers include Elliot Gould, Johnny Galecki and Brooke Langton. First time helmer, Matthew Huffman directs from a script by Mani Freedman and Carlos de los Rios, based on a play by Freedman. Sid, Bill and Jon Scheinberg of the Bubble Factory produce. No distributor has yet been set for the indie pic. Thomas’s deal was brokered by Sean Bryan of Elephant Walk Mangement and attorney Cliff Gilbert-Lurie of Ziffren, Brittenham, Branca and Fischer. Thomas is repped by Innovative Artists and co-managed by Jason Weinberg.