The actor was injured while fluffing a pillow she gave him to help him sleep while shooting the film.

Blunt, Murphy, and Robert Downey Jr were all on the ‘Jimmy Kimmel Live,’ reports deadline.com.

She said: “I just felt (what) Cillian needed, even more than food, was sleep on this movie. So I got him this very beautiful pillow that I’m obsessed with … it’s a Hastens pillow.

“He was really luxuriating in this pillow one night, and he woke up in the middle of the night — this is what he told me the next day — And he went to fluff himself back down in the pillow, misjudged where it was, and smashed his head open on the bedside table."

“So he came to work, and they had to glue his head shut!” said Blunt.

Murphy replied: “I was a bit shocked you know! I was having a great sleep, and I had this amazing pillow, strange bed, strange table, (and) bang.”

He then went on to share that the movie’s make-up artist helped mend the wound, reports deadline.com.

“We were getting up at before it was bright, like at 2 a.m. or something, 3 a.m.,” he said.

“So I called her then, and I just came in, and then she glued my head, and covered it all up, and you don’t even see it in the movie, I think.”