For his character's filibuster, Patton Oswalt improvised an eight-minute monologue linking Disney's Star Wars and Marvel movie franchises. The entire uncut take appears as an extra on the Season 5 DVD set.
When Garth Blundin (Patton Oswalt) is filibustering, he mentions a possible connection between the fictional Star Wars and Marvel universes. Patton is a regular on Marvel's TV show Agents of S.H.I.E.L.D. (2013) and is therefore part of the Marvel universe.
When Donna is talking to Ann about Game of Thrones (2011), she says that Tyrion Lannister is the Lord of Casterly Rock. That is false; Tywin Lannister never made Tyrion his heir and Casterly Rock does not currently have a lord.
When Leslie and Garth are living in Pawnee Historical House, they aren't supposed to use or wear anything later than 1817. However, Leslie's hoop skirt was not the fashion for women until the mid-19th century, at least 3 decades later.