Katie Holmes "got so red" when she forgot her lines on Broadway

Speaking on 'The Tonight Show Starring Jimmy Fallon ', she explained: "One time I didn't do it, and I was in the middle of a scene and I just said the whole line except the last word, and I couldn't remember it.

""I made something up but it didn't make sense. And then I got so red because Jim Parsons, who's delightful, he's onstage most of the time because he's the stage manager. And so I'm like, 'Oh my God. Jim knows. He's watching. And Ephraim [Sykes] knows because I was saying it to him, and then Richard Thomas. Oh God.' "

The former 'Dawson's Creek' actress was comforted by her co-star as soon as they got off into the wings, and while nobody else seemed worried about the mishap, she was.

She said: "[I] got off stage, and Jim gave me a hug after. He was like, 'I've never seen anyone say their lines so fast and remove themselves.' And nobody cared, but I cared.

"I'm like, 'This is Broadway!"

Katie also explained that some moments of the show require her to mime everyday actions, and she is "getting so sick" of using them to find the character of Mrs. Webb.

She said: "Thornton Wilder wrote this in 1938, and it takes place in 1901, and so he's written in that the mom's, like, I'm making oatmeal'. But then our director Kenny Leon was like, 'You know, I really want everyone to bring themselves to the characters.' So over time, I'm like, 'I am getting so sick of miming oatmeal."