“Welles added this remark – in the published script, it is in a footnote. [Greene wrote in a letter, “What happened was that during the shooting of The Third Man it was found necessary for the timing to insert another sentence.” Welles apparently said the lines came from “an old Hungarian play”—in any event the idea is not original to Welles, acknowledged by the phrase “what the fellow said”.
…This Is Orson Welles (1993) quotes Welles: “When the picture came out, the Swiss very nicely pointed out to me that they’ve never made any cuckoo clocks,”[29] as the clocks are native to the German Black Forest. Writer John McPhee pointed out that when the Borgias flourished in Italy, Switzerland had “the most powerful and feared military force in Europe” and was not the peacefully neutral country it would later become.” https://en.wikipedia.org/wiki/The_Third_Man#%22Swiss_cuckoo_clock%22_speech
“The Third Man” (1949) Ferris Wheel Scene 3min
Eideard 
“Welles added this remark – in the published script, it is in a footnote. [Greene wrote in a letter, “What happened was that during the shooting of The Third Man it was found necessary for the timing to insert another sentence.” Welles apparently said the lines came from “an old Hungarian play”—in any event the idea is not original to Welles, acknowledged by the phrase “what the fellow said”.
…This Is Orson Welles (1993) quotes Welles: “When the picture came out, the Swiss very nicely pointed out to me that they’ve never made any cuckoo clocks,”[29] as the clocks are native to the German Black Forest. Writer John McPhee pointed out that when the Borgias flourished in Italy, Switzerland had “the most powerful and feared military force in Europe” and was not the peacefully neutral country it would later become.” https://en.wikipedia.org/wiki/The_Third_Man#%22Swiss_cuckoo_clock%22_speech
“The Third Man” (1949) Ferris Wheel Scene 3min
“Fake penicillin, The Third Man, and Operation Claptrap” https://www.bmj.com/content/355/bmj.i6494