Joan Crawford (then on the board of PepsiCo) telephoned director Billy Wilder to protest the movie's Coca-Cola connection. Wilder then added a final scene in which James Cagney buys four bottles of Coke from a vending machine. The last bottle out of the machine isn't Coke - but another brand... of Pepsi.
Pamela Tiffin was reportedly having trouble acting with such experienced performers. Legend has it that James Cagney helped her by giving her the famous advice about acting: "Walk into a room. Plant yourself. Look the other fella in the eye and tell the truth."
Billy Wilder made James Cagney do over 30 takes of a scene because Cagney kept saying "coat and striped pants" instead of "morning coat and striped pants."
James Cagney had such a negative experience making this picture that he retired from films for 20 years until his cameo in Ragtime.
After he learns Scarlett is pregnant, James Cagney moans, "Mother of mercy, is this the end of Rico?" This was Edward G. Robinson's famous line from Little Caesar.
At one point Cagney says, "I wish I were in hell with my back broken," a line Billy Wilder used in at least two of his earlier films. Humphrey Bogart says the same line in "Sabrina", and Akim Tamiroff says a slight variation, "I wish I were in a black pit with my back broken," in "Five Graves to Cairo".
At one point MacNamara, played by James Cagney, threatens Otto with half a grapfruit so that the scene resembles the famous one in The Public Enemy, Cagney pushed into Mae Clarke's face.
At the "Grand Hotel Potemkin", the band plays the song "Yes, We Have No Bananas" (in German of course). This song is used in Billy Wilder's previous film, Sabrina
In James Cagney's autobiography, he says that Horst Buchholz was the only actor he really hated working with because he was uncooperative and tried all kinds of scene-stealing moves, which Cagney depended on Billy Wilder to correct. Had Wilder not firmly directed Bucholz, Cagney said that he "was going to knock Buchholz on his ass, which at several points I would have been very happy to do".
In addition to the "Yes, We Have No Bananas" song, Billy Wilder also borrowed the climactic switcheroo from Sabrina right down to the hat and umbrella. Piffl goes to London instead of MacNamara, just as Linus Larrabee goes to Paris instead of David Larrabee.
The Brandenburg Gate figures rather prominently in this film. It and the rest of the border between East and West Berlin were closed on August 13, 1961, only months before this film was released.
The building of the Berlin Wall during production badly hurt the film's marketing in Germany. It was very ill-received by German audiences and had minimal success during its initial run.
The building of the Berlin Wall had begun in the night of August 13, 1961, right through the set at the Brandenburger Tor. The team, discovering the change in the morning, had to move to Munich to shoot the missing scenes on the parking lot of the Bavaria Film Studios, where a copy of the lower half of the Brandenburger Tor had to be built.
The combination to the safe in C.R. MacNamara's office is 22-5-17. This is revealed when MacNamara's demands their children's and her passports to return to the United States.
The English voices of Paul Bös (Krause) and Jaspar von Oertzen (Haberdasher) are provided by John Banner.
The instruction at the front of Billy Wilder and I.A.L. Diamond's screenplay reads: "This piece must be played molto furioso". Suggested speed: 110 miles an hour - on the curves - 140 miles an hour in the straightways. "
The voice of Count von Droste Schattenburg (played on screen by Hubert von Meyerinck) is that of Sig Ruman.
To cause problems for Otto Piffl (Horst Buchholz), James Cagney gives him a cuckoo clock that plays the old English song,"Yankee Doodle," causing Buchholz to get arrested by the East Germany police. Jimmy Cagney played the lead role in Yankee Doodle Dandy, the story of George M. Cohan, the composer of "Yankee Doodle Dandy."
When Billy Wilder was at Paramount, he often clashed with an executive at the studio named Y. Frank Freeman. Freeman was from Georgia and would often brag about his extensive holdings of Coca-Cola stock. That relationship was part of the inspiration for this project.