Continuity mistake: When Diana is at the cafe with her double, the book on the table changes position between shots. Some shots the binding is perpendicular to her body and in other shots it's more parallel with it.
The Return of Maggie Beckett - S5-E9
Other mistake: The group slides to Fresno, where there is a monument to Maggie Beckett and the astronauts that were lost on an Intrepid mission to Mars. On the memorial stone, her name is misspelled as Maggie Becket, not Beckett as everywhere else.
