The movie star made her Broadway debut in the Arthur Miller play in January (10), playing a 17-year-old girl in 1950s New York with Liev Schreiber as her uncle.
And she admits she's shocked by the stunts some overzealous fans will pull in live theatre to get close to the stars.
She says, "People do weird things. We were in the middle of the second scene of the first act and we're introducing the characters and I saw in the corner of my eye something shiny falling through the audience and I thought it was maybe a light or something.
"It turns out it was some derelict with a blue guitar running to the stage and turns out he said he was a friend of mine."
Johansson refused to let the fuss affect her performance and continued with the show - and she's proud she reacted like an old theatre professional.
She adds, "I think half the audience didn't even realised it happened. The show went on."