The American-English phrase not in Kansas anymore means:
– in a strange or unfamiliar place or situation;
– undergoing a new experience.

This phrase alludes to a line from the 1939 U.S. film The Wizard of Oz¹, said by the main character Dorothy² upon realising that she has been transported from her home in Kansas, a state in the central United States, to the fantastical land of Oz—cf. also meaning and origin of the phrase ‘yellow brick road’.

The following is the page of the typescript draft for The Wizard of Oz, dated between 4^th and 6^th May 1938, on which the primary screenwriter Noel Langley³ noted the change from black and white to colour, and made Dorothy say to her dog Toto, “I’ve got a feeling we’re not in Kansas any more.”—source: National Museum of American History:

MED. SHOT – INT. FRONT DOOR
Dorothy opens the door slowly and peers out.
FULL SHOT – MUNCHKIN COUNTRY – (First full colour shot.)
quite empty of all sign of life. The only sound is the twittering of a bird or two in the distance.
MED. SHOT – DOOR – EXT.
Dorothy comes cautiously out, with Toto under her arm, and looks about. Music comes up slowly.
                      Dorothy (after a pause)
I’ve got a feeling we’re not in Kansas any more.

¹ The Wizard of Oz is an adaptation of The Wonderful Wizard of Oz (George M. Hill Company – Chicago, 1900), a children’s novel by the U.S. author Lyman Frank Baum (1856-1919) and the U.S. illustrator and cartoonist William Wallace Denslow (1856-1915).
² The character of Dorothy Gale was interpreted by the U.S. actress, singer and dancer Judy Garland (Frances Ethel Gumm – 1922-69).
³ Noel Langley (1911-80) was a South African-born U.S. novelist, playwright, screenwriter and director.

The earliest allusive use of not in Kansas anymore that I have found is from Former editor observes D.C., by Patti Sylvester, published in The Coe Cosmos (Coe College – Cedar Rapids, Iowa) of Friday 17^th September 1971:

(Editor’s note: Cosmos Associate Editor Patti Sylvester and Editor Emeritus Doug Harbit are studying off campus this term under Coe’s Washington Term program. Their observations and reports from the nation’s capital will be appearing regularly in the Cosmos this fall.)
[…]
Just flying into the D.C. airport assured me that the months here are going to be quite different from a term on campus. Washington National bears absolutely no resemblance to CR Municipal! As Dorothy said to Toto when they landed in Munchkin Land, “I’m certain we’re not in Kansas anymore. . .”

The second-earliest allusive use of not in Kansas anymore that I have found is from GOP Senator Dole wants civil disobedience?, by Lowell Ponte, published in The Columbus Telegram (Columbus, Nebraska) of Saturday 22^nd April 1972—Robert Joseph Dole (born 1923) represented Kansas in the U.S. Senate from 1969 to 1996:

Gee, Toto, we don’t seem to be in Kansas anymore. Sen. Robert J. Dole of Kansas, who in his spare time is national chairman of the be-honest-and-pay-your-debts-on-time rockribbed Republican Party is telling us ordinary people not to pay our telephone bills!
Of course, all is fair in politics (or was it love?) and war, and the Democrat-orchestrated scandal over whether International Telephone and Telegraph’s suspected contribution of $400,000 to the upcoming Republican National Convention is a strong frontal attack on a murky political battlefield. Senator Dole’s scheme is designed to block this thrust.
What does Dole want? First, he wants Americans to know that the Democratic Party still owes American Telephone & Telegraph (not to be confused with IT&T) past debts of $1.4 million from their 1968 National Convention in Chicago, and that it has made little attempt to collect these long-overdue bills. This says Dole, is tantmount [sic] to a political contribution nearly four times larger than the alleged Republican contribution by IT&T.
Second, Dole wants concerned Americans like you and me to increase AT&T’s awareness of our concern by refusing to pay our telephone bills until that $1.4 million is collected from the impoverished party of the donkey.

The phrase has given rise to the pattern we’re not in —— anymore, Toto. For example, the following is from Hotel Hershey still elegant at 60, by Randy Kraft, published in The Morning Call (Allentown, Pennsylvania) of Sunday 24^th January 1993—the Hotel Hershey (Hershey, Pennsylvania) opened in 1933:

The hotel’s ground floor lobby is modest […].
The Fountain Lobby on the main floor, which was the original lobby, is much more impressive. Anyone stepping inside is likely to murmur: “We’re not in Pennsylvania anymore, Toto.”

More generally, the name Toto has come to be used as a tag added to sentences ending with anymore. The following, for instance, is from an article by John Smyntek about Danny Bonaduce, who had just replaced Dick Purtan as host of Detroit’s WKQI-FM morning show—article published in the Detroit Free Press (Detroit, Michigan) of Thursday 28^th March 1996:

Bonaduce mocks the theory that departed WKQI morning man Dick Purtan left some big shoes to replace. Dumb, Bonaduce proclaims. “You wouldn’t talk about filling someone’s used underpants, would you?”
After 15 minutes, it ain’t the relatively straitlaced Dick Purtan show anymore, Toto.