When Hardison is unlocking his computer with voice recognition his password starts with "Glados-Alpha...". This is a reference to the puzzle-based video game series Portal, where Glados is the main antagonist.
Three members of the team are seen eating donuts and the box says Voodoo Donuts. Voodoo Donuts are well known in Portland Oregon.
The "Snake River Massacre" is also known as the "Hells Canyon Massacre." In May 1887, as many as 34 Chinese miners in Wallowa County, Oregon (northeastern-most county) were murdered by a seven member gang of men and boys. The murders took place in three camps over two days, and netted as much as $50,000 in gold (worth as much as $3.4 million in gold in 2019); supposedly, one gang member double-crossed his partners and fled with all of it. Although three gang members were tried, no one was ever convicted of the murders.
Barbara is explaining the use of a cipher to Tommy. The planted cipher used to hook them is the key to finding the lost Snake River Massacre treasure. She mentions the use of a key text such as the Declaration of Independence. The Declaration of Independence was the major plot point and key text used to find the lost treasure in National Treasure (2004).
Three guest stars in the episode appeared in Supernatural (2005-2020). Todd Stashwick (Tommy Madsen) appeared as Dracula in S4E5; Sasha Barrese (Barbara Madsen) appeared as Casey in S3E4; and Michael Girardin (Assayer) appeared as Alan in S13E16.