This line from the Pokémon episode "Haunter Vs. Kadabra";
Jessie: Oh, James, this is the greatest discovery since Einstein invented the light bulb!
In Clerks II, Randall compares a guy in a wheelchair to Anne Frank, "The chick that was all duhhh, till the miracle worker showed up and knocked some smarts into her". Dante tries to correct him by saying that was Helen Keller and that Anne Frank hid from the Nazis and had a diary. Randall then says he was right all along because the wheelchair guy had a blog.
In The Big Lebowski, The Dude is struggling with a Lenin quote ("You look for the person who will benefit...") which he cannot remember properly. Donny, trying to be helpful, repeatedly mentions Lennon's 1967 song "I Am the Walrus".
Annie: You ever heard of Walt Whitman? Nuke: Who's he play for?
An early scene in Tommy Boy has Tommy filling in the name "Herbie Hancock" on a history test question about the Founding Fathers of the United States of America. Later Tommy "corrects" someone who uses the term "John Hancock" for a signature.
In an episode of Are You Being Served?, Mr Grainger comments that a plan the staff come up with to avoid starting work earlier sounds like something Bulldog Drummond would have come up with to defeat Oscar Peterson. It has to be pointed out to him that Oscar Peterson is a pianist, and that Bulldog Drummond's arch-nemesis was Karl Peterson.
In one of the Fred Dagg radio skits, Fred mentions that Abraham Lincoln was shot by a man called Booth, who he always thought founded the Salvation Army (confusing John Wilkes Booth with William Booth for those who don't get the reference). Of course, he then follows this up by adding he might be thinking of the man who invented the telephone box.
This is combined with Composite Character as the basic concept behind the comedy RPG Diana, Warrior Princess. According to the people making a TV series far in the future, any British royal with the same name must be the same person. So Diana is married to Bonnie Prince Charlie, whose mother is Elizabeth the Queen Mother, sister to Mary Queen of Scots. In the sequel, Elvis, the Legendary Tours, Elvis' archenemy is his brother, Abbot Costello, and his companions are the left-wing John Lenin and the right-wing Joe McCartney.
In the musical adaptation of The Full Monty, the lines in "Big Ass Rock":
"I've got a friend, like Carole King, or was it Carly Simon, used to sing, I always get those two confused, but anyway—I've got a friend."
As revealed in Meet the Soldier, the Soldier of Team Fortress 2 attributes the story of Noah's ark to Sun Tzu instead:
Soldier: "Then he [Sun Tzu] used his fight money to buy two of every animal on Earth, and then he herded them onto a boat, and then he beat the crap out of every single one!"
"Lennon, the founder of Russian Communism, said that if you tell a lie loud enough and often enough people will believe it."
Not Always Right has some examples from customers, especially of museums and historical sites, including this example. While the employee never figures out what the patron actually means, they don't, despite repeated insistence to the contrary, mean to say "Machiavelli." And he wasn't French either.
In an episode of American Dad!, Stan tries to encourage his son and says:
"Just look at Helen Keller. Deaf, dumb and blind, and she wrote that whole diary in her little attic during World War II. She doesn't sound so dumb to me."
Histeria! had a character named Pepper Mills who would ask historical characters for their autograph, then realize that she had mistaken them for someone else.
Family Guy: In the song "You've Got a Lot to See", Brian sings to an old lady shut-in about all the things out in the world that she's missing. A group of wild rappers appear during the bridge listing events she's missed, including:
The Simpsons: In "Eeny Teeny Maya Moe", Marge phones Moe's and asks for Homer. Moe tries to cover by saying that he thought she was asking for Heimlich Himmler, the guy who invented the Heimlich maneuver. When Marge says they are different people, Moe claims they are both in the tavern.