When Jamie and Fergus leave to go try to help Bonnie Prince Charlie Fergus doubles back and grabs a roll to take with him. This was not scripted, but improvised by the actor.
Jamie and Jack Randall duel in France. However the last duel in France happened in the late 1300s when a noble woman claimed her husbands friend raped her. It is the subject of the 2021 film The Last Duel with Matt Damon, Ben Affleck and Adam Driver.
The title is part of a poem by famed Scottish poet Robert Burns " The best laid schemes of mice and men"