Richard Gere and Julia Roberts had obvious chemistry upon their first meeting; however, Gere was not planning on taking the role. He was on the phone ready to turn down the part when Roberts slid him a Post-it note with the words "please say yes" written on it. He accepted the role right then.
In the dinner scene where Vivian flings the snail across the room, the waiter who catches it says, "It happens all the time." Director Garry Marshall threw the snail himself over many shots before the actor caught the snail convincingly. He then cast the same actor in The Princess Diaries (2001) and The Princess Diaries 2: Royal Engagement (2004) years later and gave him the same line.
The opera Richard Gere takes Julia Roberts to is "La Traviata," about a prostitute who falls in love with a wealthy man.
In the bathtub scene where Vivian sings, a lot of detergent was used to make a lot of thick bubbles. The detergent was so strong that it rinsed the red dye out of Julia Roberts' hair. She had to have her hair re-dyed late that night.
Garry Marshall: the voiceover of the man digging through the trash outside of "Sylvester Stallone's" house (dubbed due to poor sound quality).