that train has left the station

• that train has already left the station

that train has left the station

1. That opportunity has already passed; that cannot be undone.
   • 1981 March 22, William Safire, “On Language: Do you speak ASPIC?”, in New York Times, retrieved 17 Sept 2017:

     The expression "You've missed the boat" was replaced by "That train has left the station" and will one day be replaced by "That space shuttle has already started the countdown".

   • 1994, Proposed Constitutional Amendments to Balance the Federal Budget: Floor action and committee hearings for the 101st Congress: A legislative history, Volume 4, page 533:

     Mr. Chairman, we can't prohibit borrowing by the federal government. That train has already left the station. We're too deep in debt not to borrow.

   • 2006 August 1, Susan Paynter, “Shootings can't undo the good”, in Seattle Post-Intelligencer, retrieved 17 Sept 2017:

     "This is like the Jewish United Way," Rabbi Latz said, " . . . You can't stop the Jews, or certainly the rest of humanity, from doing good. That train has left the station."

   • 2016 November 16, Adam Withnall, “Donald Trump must not make any 'irrevocable choices' over climate change, warns John Kerry”, in Independent, UK, retrieved 17 Sept 2017:

     “The enormous momentum generated by the business and investment community to address climate change cannot be reversed and cannot be ignored by the Trump administration,” he said. “That train has left the station and to stand in its way is folly.”

   • 2017 September 12, Mia Rabson, “Police ask feds to postpone date for legal pot”, in The Star, Canada, retrieved 17 Sept 2017:

     Kevin Sabet . . . said he doesn’t think Canada should legalize pot at all but if that train has left the station, Canada at the very least needs to slow it down.

• that ship has sailed

• genie is out of the bottle
• miss the boat