|"A Family Vacation"|
Without consulting the family while leaving Marty and Jennifer alone, Doc takes Clara and the boys back to medieval times (1367 A.D.) to escape the technology that he feels his family has become so reliant upon. Leaving the DeLorean that goes back to their home turf, Doc angers Clara, and Jules and Verne leave them. Once there, Clara is kidnapped by the evil Lord Biffingham of Tannenshire, and Doc is thrown into a dungeon. Jules and Verne meet up with Harold McFly, whose lady love, Jennivere, has also been kidnapped by Lord Biffingham. The boys and Harold arrive at the castle in time to witness a "jousting" match between the Lord and Doc. Clara escapes from the tower and makes a hot air balloon out of silk and a tapestry loom. When she becomes a true heroine, she rescues Doc and foils Biffingham's evil scheme. Doc realizes that he should consult her before making anymore decisions for the family. When Harold and Jennivere make up again, Doc, Clara, Jules, Verne, and Einstein head back in their home turf to visit Marty and Jennifer.
- At the end of the episode, Harold McFly (in medieval England) says he and Jennivere will have to leave. Doc suggests Ireland. The McFly family stay there until the 1880s, when Seamus and Maggie McFly move from Ireland to America. It is unclear whether this creates a predestination paradox.
- Tannenshire, Lord Biffingham's domain, was near Stonehenge in 1367. The area is located in County Wiltshire, in southern England, west of London.
- Harold says that he is one of "the Sussex McFlys". The McFlys and their descendants appear to have liked following the setting sun, moving westward from Sussex to Wiltshire (where Stonehenge and Tannenshire were located); then to Ireland; then to the United States (with at least one McFly settling in Boston); then to the western U.S., stopping at Virginia City, Nevada and eventually at Hill Valley, California.
- One of Doc's inventions seems to instantly transform everyone's clothing to a form appropriate to the era. Doc explains that hologram technology creates an illusion, and that it will wear off after 8.6 hours. The device is demonstrated again in "Dickens of a Christmas" and "Clara's Folks"
- In the live segment, Doc (Christopher Lloyd) is sailing about ten feet above Hill Valley in a balloon. The science experiment shows how to make a hot air balloon using a plastic bag, a blow dryer, and a twist tie.
New society and culture
- Hot air balloon (by way of Clara)
(Doc is facing Biffingham in an unfair jousting contest)
- Lord Biffingham: "Now, peasant, prepare to meet your ancestors!"
- Doc: "I do, quite often, but thanks for the invitation"
- Doc: "Boys, it would appear that we will have the distinction of being the first humans in history to die before we were ever born!"
- Jules: "What an honor."
Doc: Well, boys, it looks like we're short-legged, web-footed waterfowl destitute of life!
Jules: "Dead ducks."