Jerry Lewis had the only copy locked in a private vault and vowed to keep it from ever being viewed again. However, according to an article in the 8/26/15 issue of the "Los Angeles Times", he allowed this film--along with some of his other movies--to be preserved at the Library of Congress, but part of the deal was that the film would not be screened there until 2024 (as it turned out, this would make its first showing several years after Lewis' death in 2017). The Library of Congress also released a statement that it hadn't decided its specific screening plans, but would neither share the film for viewing with other government facilities nor release it for any kind of home media.

In 2008 Jerry Lewis took questions at a press conference and was asked by one person: "When are you going to release 'The Day the Clown Cried'?" to which Lewis snapped, "None of your goddamn business!"

One of the most talked-about, yet little-seen, films in history, only a select few have ever seen it. Among them was Harry Shearer, who told "Spy" Magazine that it was a "perfect object" in terms of how awful and off-tone it was. Shearer drew an analogy between seeing the film and what it would be like to take a trip to Tijuana and see a black velvet art piece showing the Auschwitz concentration camp, saying "it's not funny, and someone is trying to convey this serious event the exact wrong way."

Patton Oswalt once got his hands on a copy of the script and would perform live readings with his comedian friends playing various roles. This continued until Jerry Lewis sent him a cease-and-desist order to stop or face legal action.

After shooting began in Stockholm, Sweden, producer Nat Wachsberger ran out of money, and failed to pay Joan O'Brien for the rights to the story. Jerry Lewis was forced to finish the picture with his own money. It has been tied up in litigation ever since, and all of the parties involved have never been able to reach an agreeable settlement.

According to Jerry Lewis, he met with a man named Rolf Greiber who had pulled the lever of a gas chamber in a concentration camp. Lewis wanted to consult with him about the accuracy of the portrayal of the camps, but Lewis avoided meeting with him for six weeks because he felt he could not be in the same room with him. Greiber turned out to be very repentant about what he had done.

In 2009 Jerry Lewis agreed to be interviewed about the film for "Entertainment Weekly". He stated that while he was proud of the film, there were more scenes that he wished that he could add which were never filmed. He felt that the legend had grown so much around the film that releasing it would be unfair to everyone involved. The part of the article that concerned the film was published in 2013.

In order to lose weight for the concentration camp scenes, Jerry Lewis ate nothing but grapefruit for six weeks. He eventually dropped 35 pounds.

Chips Rafferty was offered a role in the film, but died of a heart attack just hours after receiving the news.

The circus scenes were shot at the Cirque D'Hiver in Paris where Jerry Lewis was performing at the time.

Jerry Lewis revealed in an interview for a German television documentary that he broke down emotionally at least 20 times during production.

The concentration camp scenes were filmed at a Swedish military compound.

Gene Kelly, Milton Berle, Dick Van Dyke, Bobby Darin, Al Lewis, and Karl Malden were all considered for the male lead.

Austrian/German reporter Margret Dünser visited the set of the movie in Sweden and did an interview with Jerry Lewis. She gave him a camera, and you can see Jerry Lewis in the circus arena and clowning around with the camera in her magazine V.I.P.-Schaukel: Episode #2.3 (1972) from 06/30/1972 on DVD.

Jerry Lewis hired a former SS guard as a technical assistant in order to ensure that the concentration camp set in Sweden both looked and felt real.

Jeanne Moreau was considered for the role of Anna Doork.

Jerry Lewis spent ten years working on this movie before filming began.

According to Lars Amble, who played the main Nazi guard, Jerry Lewis was convinced that Amble was perfect for the antagonistic role, as he reminded Lewis of his brother-in-law, whom he disliked.

In the book "The Golden Turkey Awards" by Harry Medved and Michael Medved, this movie was a nominee in the category "The Worst Movie You Never Saw", for movies that were completed but never released. It lost to Billy Jack Goes to Washington (1977).

At one point in the mid-1960s, Alec Guinness was attached to star and produce.

in February 2016 the discovery of an unfinished documentary by Traces Films was mentioned in several relevant YouTube comment threads. The documentary makers are Australian-based and posted their six minute-teaser on Vimeo.com in 2012. It includes exceptionally candid and emotional interview excerpts with Jerry Lewis discussing his experience making this film.

Unit photographer Roger Tillberg donated his photo negatives and production documents (shooting schedules, call sheets, etc) to the Swedish Film Institute.

On 8/5/2015, the Los Angeles Times reported that Jerry Lewis had donated a copy of the film to the Library of Congress, with the stipulation that it not be screened before June 2024. The Library of Congress intends to eventually screen it at their Audio Visual Conservation campus in Culpeper, VA. Rob Stone, curator of the Library of Congress, has stated that they will not be able to loan the film to other theaters or museums without permission from Lewis' estate. Stone has also stated that they do not intend to release the film on any form of home media.

Paul Mart and Loel Minardi were originally set to produce and direct, respectively.

It has been often said that one of the reasons this film had so many production and distribution issues was that many people had a problem with comedy being mixed into a film about a subject as serious as The Holocaust.

Jan Malmsjö was originally cast as Johann Keltner, but bowed out before filming began and opted for a smaller role instead.

Peter Berneis worked on an earlier draft of the script.

Despite a similarly grim subject matter, another holocaust film, 'Jacob the liar' (1974) with a blackly comedic edge was made and released two years later. This was remade in Hollywood as 'Jakob the liar' (1999) 25 years later with Robin Williams in the lead role.