The "Knocked Up" star plays Elvira Condomine in the film adaptation of Noel Coward's 1941 play and she struggled to keep her cool in her first scenes with Dench, who portrays mystic Madame Arcati.
Leslie told talkRADIO, "It was so much fun, the first day I worked with her was in bed and that was terrifying for me because she's someone who I have so much respect for and there I was laying in bed with her."
"I think she knew I was nervous, I was probably sweating or something, and she went out of her way to make me feel comfortable and she set me at ease," she continued. "It took me about an hour and a half to calm down, because it's too close up, she was right there!"
Aside from struggling with her jittery when sharing scene with Judi Dench, Leslie Mann enjoyed most of the filming. She especially relished wearing the period outfits. "It was exciting to learn something new and a new way of doing things. All the costumes were so much fun, incredible to wear something other than what my characters would normally wear like jeans or t-shirts," she said.
"It was so much fun to wear the beautiful feather capes and the gorgeous high waisted trousers and blouses and just the whole thing. It was like a dream, so much fun!"