Other mistake: At the end of this episode when Jonathan and Nicky set off on horseback to the canal to board the tug boat "Heartsease" they leave late at night and arrive the next day. But in episodes 7 and 8 Margaret rides on horseback to Heartsease and home again, and the journey only takes a few minutes.
Revealing mistake: Whenever Isis has to do jumps you can tell it's not her but a stunt double.