In recent years however, he has been incorporated into the Society of Explorers and Adventurers storyline in the parks and appeared as a main character in Disney Kingdoms: Big Thunder Mountain Railroad.
Behind the Scenes
Jason Chandler was created in the 1970s by Tony Baxter as part of a major expansion for Disneyland, linking Discovery Bay and Big Thunder Mountain's storylines.
The Spring 1992 issue of Disney News described this backstory for Thunder Mountain thusly:
The highly imaginative tale includes the legend of a young inventor, named Jason Chandler, who lived in a town called International Village during the peak gold rush years in the Big Thunder region - circa 1849. According to the chronicles, "...the young inventor devised a drilling machine with the capability of boring into the very heart of Big Thunder Mountain. There, the veins of gold ran so deep, it was rumored they could produce a mother lode that would bring a man enough wealth to last a hundred lifetimes and more."Chandler as it turns out, survived the incident and knowing how many lives were wasted in pursuit of the gold, chose to use it to better mankind, establishing a scientific outpost in northern California named Discovery Bay and funding research into strange and unusual technologies and salvaging the remains of the Nautilus and continuing Nemo's scientific work.
But a cave-in occurred on Big Thunder, burying 26 miners alive. They would have drawn their last breath then and there, had it not been for the inventor and his laughable drilling machine. He burrowed down into the Earth’s core, rescuing the miners from certain death. It should have been a moment of joy and celebration, but as the men scrambled to the arms of safety, a massive earthquake shook the ground and a cavernous maw opened up, swallowing the inventor and his machine whole."
The miners, as well as the citizens of the village, struggled day and night against the mountain, trying to dig the young man from his living tomb. But they never saw him, or another nugget of gold, again. Big Thunder had taken its vengeance not only on the miners, but on their wealth as well. The mountain had gone bust, and it became just a matter of time before only ghosts resided there.
The land would also be accompanied by a television miniseries, The Discovery Bay Chronicles, which would tell the story of the area with only a pilot starring Pete Renaday as Chandler being produced. However, everything was cancelled in the wake of the failure of the film The Island at the Top of the World, which would have served as the headliner attraction to the expansion. With the loss of Discovery Bay, Jason Chandler and his drilling machine would also be written out of Big Thunder Mountain. Years later, as the Society of Explorers and Adventurers storyline was developed by Imagineering, Jason Chandler would be incorporated into their membership, being described as the leader of the late 1800s-era version of the group.
Big Thunder Mountain Railroad (Magic Kingdom)
He doesn't make a direct appearance, but letters in the queue from Jason Chandler to Barnabas T. Bullion have him discussing the drilling machine he sold to him and warning him that with all the supernatural incidents, it might be better to move mining operations away from the mountain.
"Dear Barney, Great Caesar’s Ghost, old chap, I haven’t heard from you since our little misadventure in El Dorado! I am indeed sorry to hear of the second disturbance within Big Thunder Mountain, but I did warn you that you were prospecting at your own peril when I sold you the drilling machine. I took the liberty of consulting Madame Zarkov at the Museum of the Weird, and it is her considered opinion that you should abandon the entire operation at once and find a less volatile site. I wish I had better news for you, old boy, but some forces simply are not to be trifled with.
On behalf of your compatriots of SEA, I do hope to see you around the club a bit more often!
Yours in Exploration and Adventure,
Founding Member The Society of Explorers and Adventurers"
Other theme park references
A red stagecoach appeared along Big Thunder Trail, the path to the entrance of Star Wars: Galaxy's Edge closest to Fantasyland, when it reopened in July 2017. A trunk on top of the stagecoach has a tag reading "Deliver to Jason Chandler."
In the SEA room of the Magic Kingdom's Skipper Canteen, a map produced by Jason Chandler and Captain Brieux of the Hyperion airship charting Legendary Flying Beasts in the Mekong River can be found on the wall.
In Disney Kingdoms: Big Thunder Mountain Railroad, Jason Chandler is one of the miners working for the Big Thunder Mining Company and Barnabas T. Bullion. However, with the dangerous working conditions for small pay, he and other like-minded citizens of Rainbow Ridge have been robbing gold shipments to share the wealth with the townspeople and recruits Abigail Bullion to the cause of undermining her father.