Jane Fonda claims that the scene between Chelsea and Norman (Henry Fonda) where she tells him she wants to be his friend mirrored the real-life relationship between father and daughter. During one take when the younger Fonda unexpectedly grabbed her father's hand, Henry Fonda started to cry and ducked his head away from the camera, embarrassed by his tears. The take appears in the final film.
The brown Fedora worn by Henry Fonda belonged to Spencer Tracy and was given to Henry Fonda by Katharine Hepburn on the first day on the set. Henry Fonda, overwhelmed with the gesture, painted a still life watercolor of the three hats he wore in the film and gave the original to Katharine Hepburn as a gift. He had 200 lithographs made of the painting and sent one to every person who worked on the film. Each copy was numbered and personally signed by Fonda thanking each person by name. In her autobiography, Hepburn wrote that she gave the painting to screenwriter Ernest Thompson. After Fonda's death, she found the painting to be a sad reminder of him and Spencer Tracy.
Henry Fonda won the Oscar for Best Actor in a leading role for his role as Norman Thayer, Jr. At 76 (actually 76 years and 317 days), he was the oldest actor to win the Best Actor Oscar. He is also the only actor to win the Best Actor Academy Award aged in his seventies. Fonda though is not the oldest actor to win an Academy Award for acting as George Burns won a Supporting Actor Oscar for The Sunshine Boys (1975) at age 80 (actually 80 years and 69 days).
Katharine Hepburn hurt her arm in a tennis match a few weeks before filming. She almost pulled out, but Henry Fonda convinced her to show up to start shooting on day one. One scene was omitted from the film in which you see her pick up a canoe by herself with her sore arm. She never forgave Mark Rydell for editing that scene out.
The Purgatory Cove scene was shot in late September. To keep warm in the cold water both Doug McKeon and Henry Fonda had to wear wetsuits under their clothes. However, the water level was so low that they could have easily stood up and been only knee-deep in the lake. Katharine Hepburn was supposed to have a stunt double perform her "dive-in" scene for her, but instead she insisted on doing it herself. She dove into the frigid water without a wetsuit.
In the scene near the beginning of the film where Norman Thayer (Henry Fonda) calls the operator to see if the phone is working, he looks at a framed photograph on the desk and asks "Who the hell is that?" While the picture presumably is an old photo of Norman, his wife, Ethel (Katharine Hepburn), and their daughter Chelsea (Jane Fonda), the photo (circa 1941) actually shows Fonda and four-year-old Jane with Fonda's real-life second wife (and Jane's real mother), Frances Seymour Brokaw.
Henry Fonda currently holds the record for the longest gap between acting Oscar nominations. His first nomination was for The Grapes of Wrath (1940) in 1940, his second was for On Golden Pond (1981) in 1981, 41 years later. He received one other Oscar nomination in the period between his two acting nominations, that was for producer of 12 Angry Men (1957) in 1957.
Gertrude, the canoe featured in the film, was included in a lot of the estate of Katharine Hepburn during the two-day auction hosted by Sotheby's in 2004. The canoe was sold for $19,200 to entertainer Wayne Newton.
Charges were set at the front of the Thayer's boat so that it blew up prior to hitting the big rock in Purgatory Cove. The vintage wooden U22-Sportsman Chris-Craft boat proved so durable that it bounced off the rocks without any damage during the early takes of the scene.
Walter the Trout was brought over from a local trout pond at the Castle in the Clouds in Moultonboro, New Hampshire. Billy and Norman really threw him back into the lake. People still hope to catch him, but after all these years the fish would be a distant relative.
The movie's line "Listen to me, mister. You're my knight in shining armor. Don't you forget it. You're going to get back on that horse, and I'm going to be right behind you, holding on tight, and away we're gonna go, go, go!" was voted as the #88 movie quote by the American Film Institute (out of 100).
Later produced as a live TV production - rare for TV theatrical presentations since the invention of videotape in the late 1950s. It starred Julie Andrews and Christopher Plummer (who had previously co-starred in The Sound of Music (1965)) and was broadcast on CBS on April 29, 2001.
Universal's big Christmas release of 1981; Conan the Barbarian (1982) was supposed to have it instead, but when Universal deemed the film too violent for a Christmas release, it was pushed back for release in 1982.