History YMMV / WhatsMyLine

** When Creator/JulieAndrews was the special guest, they asked if she was known for her work in motion pictures, and she answered no. This episode aired four years before Film/MaryPoppins ended up making her a household name and completely overshadowing her Broadway career.

** The interview with Creator/SeanConnery after he's identified on the 3 October 1965 episode. Now that we know he was tired of playing Film/JamesBond by that point, it's obvious that the whole time he's desperately trying to [[AdamWesting turn the conversation towards his other work]], only to keep getting roped back into talking about Bond.
** Robert Morse puts on a fake deep voice to hide his identity when he was the Mystery Guest on the 12 March 1967 episode, which sounds quite similar to how deep his voice really did get in his later life.
** As noted on the main page, [[Series/SesameStreet Big Bird]] was a mystery guest on one episode. Bennett Cerf's son, Christopher, would later become a prolific composer for ''Sesame Street.''

** [[UsefulNotes/KentuckyFriedChicken Colonel Sanders]] appeared as a guest on the 1 December 1963 episode as a "regular person" guest contestant before he was a household name.
** The Sept. 16, 1956 episode opened with Creator/JacquesCousteau as the first guest. Since Cousteau was not familiar to the panel (Cousteau had signed in as Mr. X), all of them were stumped.

* WTHCastingAgency: The appearance of actress Pamela Tiffin as a panelist on the March 12, 1967 episode. Commenters on Website/YouTube have called her one of the worst panelists in the history of the show, due to her poor game play and a number of on-air gaffes (including forgetting to introduce Bennett Cerf at the beginning of the show).

** On the November 2, 1958 episode, John Daly congratulated Mystery Guest Creator/RobertWagner on his recent wedding to Creator/NatalieWood and hoped they would have a long and happy marriage. As both of their pages note, Wagner and Wood's marriage went through considerable turmoil and ended with Natalie tragically drowning in 1981.

* InformedRealLifeFame: Modern viewers of the reruns may experience this when the mystery guests turn out to be long-forgotten teen heartthrobs or Broadway stars.

* InformedRealLifeFame:
** Modern viewers of the reruns may experience this when the mystery guests turn out to be long-forgotten teen heartthrobs or Broadway stars.
** Also {{Inverted|Trope}} on the 1 December 1963 episode, where the "regular person" guest contestant was a little-known restaurant owner named [[UsefulNotes/KentuckyFriedChicken Colonel Harland Sanders]].

** As mentioned above, Colonel Sanders of Kentucky Fried Chicken fame appeared as a guest before he was a household name.

* As noted on the main page, [[Series/SesameStreet Big Bird]] was a mystery guest on one episode. Bennett Cerf's son, Christopher, would later become a prolific composer for ''Sesame Street.''

* HarsherInHindsight:
** On the April 4, 1965 episode, John Daly said to the mystery guest that night, Maurice Chevalier: "I just hope that when I am 77 (sir, if you will forgive me), that I have your ebullience of spirit, your perennial and wonderful youth, and that glorious confidence". Daly died four days after turning 77 in 1991.

* InformedRealLifeFame: Modern viewers of the reruns may experience this when the mystery guests turn out to be long-forgotten teen heartthrobs or Broadway stars.

* RetroactiveRecognition: As mentioned above, Colonel Sanders of Kentucky Fried Chicken fame appeared as a guest before he was a household name.

* WTHCastingAgency: The appearance of actress Pamela Tiffin as a panelist on the March 12, 1967 episode. Commenters on YouTube have called her one of the worst panelists in the history of the show, due to her poor game play and a number of on-air gaffes (including forgetting to introduce Bennett Cerf at the beginning of the show).

** The Sept. 16, 1956 opened with Creator/JacquesCousteau as the first guest.

** The interview with Creator/SeanConnery after he's identified on the 3 October 1965 episode. Now that we know he was tired of playing Film/JamesBond by that point, it's obvious that the whole time he's desperately trying to turn the conversation towards his other work, only to keep getting roped back into talking about Bond.

** On the April 4, 1965 episode, John Daly said to the mystery guest that night, Maurice Chevalier, "I just hope that when I am 77 (sir, if you will forgive me), that I have your ebullience of spirit, your perennial and wonderful youth, and that glorious confidence". Daly died four days after turning 77 in 1991.

** On the April 4, 1965 episode, John Daly said to the mystery guest that night, Maurice Chevalier, "I hope when I am 77, I have your ebullience of spirit, your perennial and wonderful youth, and that glorious confidence". Daly died four days after turning 77 in 1991.

** On the April 4, 1965 episode, John Daly said to the mystery guest that night, Maurice Chevalier, "I hope when I am 77, I have your ebullience of spirit, your perennial and wonderful youth, and that glorious confidence". Daly died four days later after turning 77.

** Also {{Inverted|Trope}} in one episode, where the "regular person" guest was a little-known restaurant owner named [[UsefulNotes/KentuckyFriedChicken Colonel Harland Sanders]].

** Also {{Inverted|Trope}} in one episode, where the "regular person" guest was a little-known restaurant owner named Colonel Harland Sanders.

** The interview with Sean Connery after he's identified. Now that we know he was bored sick of playing James Bond by that point, it's obvious that the whole time he's desperately trying to turn the conversation towards his other work, only to keep getting roped back into talking about Bond.
** Robert Morse puts on a fake deep voice to hide his identity, which sounds quite similar to how deep his voice really did get in his later life.
* InformedRealLifeFame: Modern viewers of the reruns may experience this when the mystery celebrities turn out to be long-forgotten teen heartthrobs or Broadway stars.
** Also inverted in one episode, where the "regular person" guest was a little-known restaurant owner named Colonel Harland Sanders.
* TheyChangedItNowItSucks: Some fans of the classic series aren't too fond of the 1968-75 syndicated version due to the reduced emphasis on formality (panelists dressed more casually and were referred to on a first-name basis) and the demonstrations of new inventions (which was never done on the original series due to John Daly not being fond of the practice) making it too similar to ''Series/IveGotASecret'', to the point where they nicknamed it ''What's My Secret Line?''

** Also inverted in one episode, where the "regular person" guest was a little-known restaurant owner named Colonel Harland Sanders.

** The interview with Sean Connery after he's identified. Now that we know how much he hated playing James Bond by that point, it's obvious that the whole time he's desperately trying to turn the conversation towards his other work, only to keep getting roped back into talking about Bond.

** Also inverted in one episode, where the "regular person" guest was a little-known restaurant owner named Colonel Sanders.

* HilariousInHindsight: The interview with Sean Connery after he's identified. Now that we know how much he hated playing James Bond by that point, it's obvious that the whole time he's desperately trying to turn the conversation towards his other work, only to keep getting roped back into talking about Bond.

* InformedRealLifeFame: Modern viewers of the reruns may experience this when the mystery celebrities turn out to be long-forgotten teen heartthrobs or Broadway stars.