For years, a fan theory has held that the foundational event in both "Back to the Future" and "The Goonies" — traveling to the past and entering an underground world, respectively — occurred on the same day: Oct. 26, 1985.
"Back to the Future" follows Marty McFly as he travels, in his scientist-friend's time machine, from 1985 to 1955 and back again. "The Goonies," also set in 1985, follows a group of adolescents who, on their final weekend before their parents' eviction to make way for a country club, go underground on a treasure-map-aided adventure in a saga involving a pirate ship and a crime family named the Fratellis. The production company on both films is Stephen Spielberg's Amblin Entertainment.
The day Marty McFly travels from (and to) in the "Back to the Future" series is indeed Oct. 26, 1985, as displayed in Doc's time machine. This aspect of the claim is not controversial:
The claim that the Goonies go underground on their adventure on this same day comes primarily from a newspaper article in the movie that describes the jailbreak and off-road car chase of Jake Fratelli, of the Fratelli crime family, depicted at the start of the movie. That article bears the date Oct. 24, 1985:
In our reality, Oct. 24, 1985 was a Thursday. The Goonies' story, we know from several explicit statements in the film, begins on a Saturday. This is established, among other ways, by the character Mouth's opening line in the film:
Lookit' you guys lyin' around like it was nuclear Saturday! C'mon dudes! This is our last weekend together!
Because Oct. 24 was a Thursday, the theory holds that the movie's main story takes place two days after the events described in the paper, or Oct. 26, as recounted by SyFy:
One especially big tell comes in an easy-to-miss scene from The Goonies, when a newspaper dated “Oct. 24, 1985” (a Thursday) is shown alongside an article reporting on the felonious misadventures of the Fratelli crime family.
[...] The action of The Goonies unfolds on a Saturday, leading sharp-eyed fans to logically conclude that the Fratelli story in the newspaper is hot off the presses — only two days old, in fact, by the time viewers (and the kids) see it.
This is impossible, as the car chase described in the newspaper article, the one depicted in the beginning of the film, explicitly happens on the same day that the movie's main action occurs. This is clear not only from the fact that the Fratellis' off-road vehicle (O.R.V. in the script below) is seen driving away in the same shot that first shows the character Mikey's house, but also in the stage directions of the actual screenplay for the film, which clearly states that Mikey "just missed" the chase:
For these reasons, the events described all must happen on the same day, and that day must have been a Saturday. The only conclusion, then, is that in the Goonies universe, Oct. 24, 1985 was, for whatever reason, a Saturday. Indeed, there is further support for that notion.
Following the release of the film, a novelization of "The Goonies" was also released. This book, written by James Kahn, was based not on the final film, but the full screenplay, and included material that was cut from the movie. The book's prologue, conveniently, provides the full text of the newspaper article briefly shown in the film, and it clearly defines Oct. 24, 1985 — for whatever reason — as a Saturday:
(The Goonies, Kindle Edition)
In another section of the book, the eviction notices that residents of the "Goon Docks" receive are described as listing the day they "had to be out" as Oct. 25, (i.e., the following Sunday), further solidifying the structure of October 1985 in the Goonies universe. The newspaper shown had to have been a late edition from the same day — even more "hot off the press" than SyFy described.
While Snopes has no answer for why the filmmakers decided to write a film about a weekend that takes place on a date that was not the weekend in reality, claims that two days pass between the chase and the Goonies' subterranean adventure are explicitly not possible, based on context in the film itself, the screenplay, and a novelization of that screenplay.
As such, "Back to the Future" and "The Goonies" do not share a temporal link surrounding the date Oct. 26, 1985, and the claim is false.