As of 2019, 'Gettysburg' is the second-lowest-rated episode, after only the clip show 'The Banker' in season 6.
The northernmost battle of the Civil War was fought in St. Albans, Vermont, on October 19, 1864. A group of 22 Confederate soldiers, led by Lt. Bennet H. Young, crossed from Canada into St. Albans, shot up the town, and robbed three banks of more than $200,000. They attempted to burn the village, but townspeople prevented this destruction. Eleven members of the group escaped back into Canada where they were arrested and later released. On a grander scale, the Battle of Gettysburg was the northernmost major engagement.
Darryl asks a ranger about the significance of the peach orchard. Dwight interrupts before the ranger can answer, but the orchard provides access to various memorials regarding the momentous attacks and counterattacks in the orchard on the afternoon of July 2, 1863.
When discussing his Big Mac idea, Kevin says that a person who makes a Big Mac at the end of the week from the ingredients from previously bought Big Macs would love it more as it would be made by himself/herself. This is a case of the Ikea Effect - a cognitive bias in which consumers value products partially created by themselves disproportionately high.
The drive from Scranton to Gettysburg is actually approximately 164 miles and would take about 2 hours and 40 minutes. When the bus pulls into Gettysburg, Daryl says the movie (Limitless) is almost over, but the movie actually has a runtime of only about 105 minutes.