"We're in a sound stage and a green screen with a little red car with two heads in it. I sent my team out, and they actually shot...the entire journey, so everything we plugged into the movie was legitimately where we were," said director Anne Fletcher.
It took the filmmakers about a year to get Streisand to say yes to the project.
"Because I said I wanted to stay in my home. I mean, I don't have to do it, so I kept saying no and putting up these hurdles that they always jumped over," said Streisand.
Fletcher said she told Streisand to do it for her fans.
"At one point, I just said, 'Your fans need you in this movie. They need to see you in this movie,'" said Fletcher.
Fletcher said she and Streisand had a "great, cohesive, collaborative relationship" while shooting the film.
"The level of respect that she gave me from beginning to end was extraordinary," said Fletcher.
"The Guilt Trip" is now in theaters.