He went out and purchased a hundred handkerchiefs and distributed them to the production crew, and told them if they felt like they were going to laugh, to stuff the handkerchief in their mouth!
It worked well, but he didn't get one for himself, and in the part of the movie where they are all sitting at the table eating dinner, and Dr. Frankenstein is disconsolate because his experiment failed, Terri Garr says kindly to him "You haven't even touched your food." Gene Wilder improvised and repeatedly stuck both hands in his food saying "There! I've touched it!" and Mel Brooks himself nearly ruined that perfect shot, but was able to somehow suppress his laughter!"
They said Marty Feldman as Igor was another one who was constantly causing people to laugh resulting in re-shoots.
Almost every actor involved said they had so much fun working on that.
Lots of good stuff there. He said he got the studio to fund the movie, and after they all shook hands and he walked out, he casually said "And I'm going to shoot it in black and white!" they went berserk!
Brooks, who is Jewish, said "I had a dozen Jews running down the hall after me, simultaneously yelling at me that the deal was off!"
I always found this part funny:
Every time someone would say "Frau Blucher" in the movie, you could hear in the distance, the horses go crazy, because they thought "Blucher" somehow meant "Glue" in German, but Brooks said that wasn't true...:) I forget why he said they had that part...
He also talked about how Gene Hackman (at the height of his popularity due to The French Connection) heard about the movie and desperately wanted to be in it, so Mel Brooks gave him a bit part that I think was uncredited, and most people didn't know it was him! (he was the old blind guy who spills hot coffee in the monster's lap!)