Australian actress Isla recently gave birth to her second child with comedian husband Sacha Baron Cohen, but Simon - who had no idea she was pregnant when they filmed their love scene for the movie- joking said he feared he hadn't learned about sex properly.
He told The Sun newspaper: "I was worried my sex education classes were wrong, apparently you can get up the duff without actually having sex!"
Simon also said he tries to get his dog, Minnie, to appear with him in his movies.
The actor - who will appear in Steven Spielberg's and Peter Jackson's big screen adaptation of comic book character Tintin in 'The Adventures of Tintin: The Secret of the Unicorn' - revealed his schnauzer Minnie "does it for the love" of acting.
He said: "I keep trying to get her in the films. I took her to New Mexico last year, I took her to Los Angeles. There is no fee for her, she does it for the love."