Well, it’s a tradition in this thread for there to be multiple valid answers!
We’ve got 3 for this one!
Hot Springs, AR is not volcanic.
- Jimmie Finlayson, Mae Busch, Ben Turpin, Buster Keaton
Ben Turpin, but I can’t remember why.
Ben Tupin was the only one with crossed eyes. Or it’s Buster Keaton, who’s the only one who didn’t work for Mack Sennett (and may be the only one one who was never hit in the face with a pie). Or Mae Busch, the only female. Or Finlayson, who was not a natural born US citizen.
Bandarnaike was not Prime Minister of India; he’s the only Sri Lankan. Gandhi was the only woman.
Naked Came the Stranger was fiction. It was also published pseudonymously, and is the only one with more than 20 recorded authors. The Kama Sutra was published anonymously and was not originally published in English, and I don’t believe it was ever a NY Times Best Seller, like the others. The Kinsey Report is the only one whose original name is not listed (It was two books – Sexual Behavior in the Human Male and Sexual Behavior in the Human Female). Everything You Wanted to Know about Sex . . . was the only one made into a comedy film.
“Woomik” is not an American Football term. A forward lateral is the only illegal play. T-formation is the only one that describes the way the player can line up.
Really, you can pick just about any one of the items as being different.
Buster Keaton never worked (so far as I know) with Laurel & Hardy.
(Jimmie Finalyson not a natural-born American citizen? Was he Canadian??)
Naked Came the Stranger was the only book not a discussion of sexuality.
And I did mean for Bandaranaike to be the odd one out, for the reason you stated.
As for Woomik–What, Me Worry? 
Scottish.
- Belle Poitrine, Bubber, Magdalena Montezuma, Letch Feeley
Bubber (First Lady) was not a character in Patrick Dennis’ Little Me. -
Collier’s, Liberty, Scientific American, Quinto Lingo
Scientific American is not a defunct magazine. - Perfective aspect, stem-changing verbs, preterit, personal a
- Perfective aspect is a term used in Russian grammar. The others are from Spanish grammar.
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Good Times, One Day at a Time, Welcome Back Kotter, The Jeffersons
Welcome Back Kotter is the only non-Norman Lear sitcom.
- Alpha-Bits; Apple Jacks; Honeycomb; Grape Nuts
Apple Jacks, as one poster noticed, is the only Kellogg’s cereal.
- T-formation; first down; woomik; forward lateral
Doesn’t anyone remember 43-Man Squamish?
- Hot Springs National Park, Arkansas; Iquique, Chile; Iceland; Yellowstone National Park
Iquique is the only one of the four places without water. - Oliver Ellsworth; Michael Musmanno; Morrison Waite; William Howard Taft
Justice Musmanno was never a Chief Justice of the United States–unfortunately.
Here’s another set of ten: - Rear Window, Vertigo, Psycho, It’s a Wonderful Life
- Osceola, Tallahassee, Key West, Phenix City
- Bobo Newsom, Bob Feller, Eddie Cicotte, Bill Dinneen
- Fort Ord, Vandenberg AFB, Otis AFB, Camp Pendleton
- Mort Drucker, Al Jaffee, Don Martin, Don Orehek
- Latissimus dorsi, gastrocnemius, vagus, sternocleidomastoid
- Amminadab, Zebulun, Issachar, Simeon
- Oklahoma!, Carousel, My Fair Lady, South Pacific
- Cacciatore, Arroz con Pollo, Hassenpfeffer, Campbell’s Noodle Soup
- Mike Mansfield, Jacob Javits, Hillary Clinton, Bobby Kennedy
Psycho didn’t star Jimmy Stewart
I be;lieve Don Orehek drew in Cracked Magazine, not Mad, unlike the others.
And *It’s a Wonderful Life * was the only non-Hitchcock film
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It’s a Wonderful Life was directed by Frank Capra, the others by Alfred Hitchcock.
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Phenix City is in Alabama, while the others are in Florida.
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I believe Bill Dinneen was an umpire. I know the others were pitchers.
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Otis AFB is not in California.
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My Fair Lady was written by Lerner and Loewe, not Rodgers and Hammerstein.
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Hassenpfeffer is rabbit, while the other dishes contain chicken.
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All were/are U.S. Senators, but Mansfield was from Montana, while the others represented New York.
Also possible:
Javits was a Republican, the others on the list are Democrats.
Dinneen was a pitcher too, before his umpiring days. Try again. 
- Latissimus dorsi, gastrocnemius, vagus, sternocleidomastoid
Vagus is a nerve, the rest are muscles
The capitol of Missouri is Jefferson City.
Well, there is that little river we call the Mighty Mississippi. The Big River. The Big Muddy. You’ve probably heard of it.
- Unlike Bill Dinneen (1903), Eddie Cicotte (1919), or Bobo Newsom (1940), Feller never won a World Series game.
- Amminadab was not one of Jacob’s sons.
Here are the next ten: - William King, Spiro Agnew, Hannibal Hamlin, John C. Calhoun
- KISS, the Royal Canadians, AC/DC, Darryl Hall & John Oates
- Janice, Topo Gigio, Dr. Bunsen Honeydew, Dr. Strangepork
- 1804 silver dollar, 1922 quarter, 1894 dime, 1913 nickel
- Camille, Katrina, Andrew, Susquehanna
- Rocky Road, divinity fudge, dulce de leche, tin roof sundae
- Roe v . Wade, Stogner v. California, State of New York v. Kringle, Mapp v. Ohio
- Dan Rowan, Woody Guthrie, Ted Knight, Audie Murphy
- Fold-In, Snappy Answers to Stupid Questions, The Hate Book, Quivering Quotations
- Wassail bowl, yule log, the dropping ball, reindeer
- Janice is from Rocky Horror. The others are from the Muppet Show.
- Some of these cases are fictional. One is not. However, I can’t tell which one, and I will not google it, so nevermind.
- The dropping ball is from New Years, all others are from Christmas.
I’m not sure who William King was, but the other three were all U.S. Vice-presidents, and I think they were all “replaced” by other VPs under the same president (Hamlin by Andrew Johnson, Agnew by Gerald Ford).
Online sources are unclear about whether the Electric Mayhem guitarist’s name is spelled “Janice” or “Janis.” If this is who you are referring to then I’ll pick Topo Gigio as the only non-Muppet.
The first two, at least, are Mad Magazine features written & drawn by Al Jaffee.
Susquehanna was the name of a hat company, not a hurricane.