Alfred Hitchcock learned the hard way that leading cats was not one of his talents

While in theory it might sound great to have a symphony of cats running together, the plans were nearly impossible to orchestrate. Although Hitchcock put up barriers to contain the cats, they proved to be less effective. He told Truffaut that:

"We put flat panels all the way around the bottom of the stairs. Each owner came forward and put their cat in the stall, and then we were ready to film. The cameraman turned on his motor and the prop guy fired a gun. All the cats jumped over the fence, none came up the stairs. They were all over the studio. And for the next few hours, all you could hear was was the owners walking around saying, "Puss, pussy, pussy."... Eventually we got them all together again, and this time we had a fence put up so they couldn't run away. Everything was ready. Camera. Bang! This time only three cats made it up the stairs. All the rest turned around and clung desperately to the net. So I gave up."

The idea of ​​a hundred cats running around a movie studio can be hilarious, but it's also a huge hindrance. Given the circumstances, it's no surprise that Hitchcock chose to delete the shots with the cats - even though the end result would have been a great display of deft editing. And while viewers may have missed a few laughs, the story itself is definitely funny enough to make up for it.