Something I would probably want a house rule, or maybe even an official ruling, on is the combination of Ferries with Magic Portal. I don't think it should be permitted to deploy a follower through the magic portal to a road which is otherwise completed except that the ferry needs to be toggled.
The magic portal
A player who places a magic portal tile may deploy a follower in this turn to
that tile or to a tile already in play.
The usual rules must be followed—for example, the
follower may not be
deployed to an already occupied or
completed road, city, cloister, or farm
The ferries
Continuing a road with a ferry – If, by placing a tile, a player
continues a road where there
is a ferry, that player may move the ferry.
...using the magic portal and then move the ferry - that doesn't work.