Originally, Snuffy was to be seen only by Big Bird and no one else believed Big Bird that Snuffy was real. But then the producers decided to make everyone see Snuffy because they thought it was sending a bad message to kids that adults won't believe them when they have something important to say.
The adults said that Mr. Hooper died instead of saying he passed away because the staff thought that their young viewers didn't know what "passed away" meant.
The whole segment where Big Bird finds out about Mr. Hooper's death was filmed in one take.
A child psychologist was sent to help the writers with the segment where they talk about Mr. Hooper's death. He told them not to say that Mr. Hooper died in a hospital because it would cause children to become scared of hospitals. Also, he said that they should air the episode during a holiday so that parents could be at home to talk to their children about death. So that is why this episode was aired during Thanksgiving.
All of the drawings that Big Bird drew of the adults were made by Caroll Spinney, the actor who plays Big Bird.
The staff were thinking about showing flashback scenes of Mr. Hooper, but they decided not to because they thought it would confuse their viewers.
The producers were planning on telling the viewers that Mr. Hooper moved away or replacing him with a different actor until they decided to tell everyone that he passed away and they created the segment where Big Bird learns about death.
The segment of Big Bird finding out that Mr. Hooper died was adapted into a children's book called, "I'll Miss You, Mr. Hooper".
When the adults are talking to Big Bird about Mr. Hooper's death, they were almost in tears because they were still grieving over Will Lee, the actor who played Mr. Hooper.
In the "Mad Painter #4" segment, the 4 on the woman's umbrella changes in the shot after he paints it. In fact, it looks like he didn't just paint it.
The street segment with Big Bird asking a boy what big and little mean doesn't belong in this episode, in which it rains throughout the episode. Perhaps it was not in the original PBS cut.