"The audition tapes, probably only 10 people on Earth have seen them, prior to today," Ron Howard, director of the mermaid comedy, says on the DVD, noting his assistant always keeps tapes of the actors trying out for roles in his films.
"They're like little treasures," he says. "And also, I think, they're really good indications of what good actors they are because they're good in the auditions, Tom and Darryl."
In one tape, Hanks spends most of the time acting alone against a blank wall, while Howard reads the other actors' lines aloud.
In the Hannah tape, Howard appears on-screen to read with the actress.
The DVD will be released on March 23.