Though Simone, a 17th century Frenchwoman, speaks English with an adopted French accent, Stana Katic actually can speak French, and it is one of five foreign languages in which she's fluent.
A plesiosaur can be seen swimming in the pool in the last shot of the library floor. In a later episode of the follow-on series, Jenkins mentions that the largest animal they have in the library is Nessie, a.k.a. the Loch Ness Monster. Nessie believers have speculated that the monster might actually be a plesiosaur.
The Judas Chalice prop later appeared in the Leverage (2008) episode "The First David Job (2009)". Both projects were produced by Dean Devlin.
During the swordfight, Flynn's stance is that of an epee/foil fencer (with his off hand held above his shoulder); his opponent uses a saber fighter's stance (with his off hand on his hip).
Establishing shot of Glenn Estate shows a white castle-like building. That was the Louisiana State Capitol Building from 1852 to 1932. This Baton Rouge landmark is now a museum.