Q:

Obscuring the ball from the opponent

Can a player pretend to pass the ball to another and the second player pretend or act as if they have it, while obscuring the ball from the opposition?
I was watching the animated TV series All Out!!/オールアウト!! (a show about a rugby team) and they did such a manoeuvre.
Was this legal?

A:

As a referee, having looked at that it's not at all illegal. It is the equivalent of a dummy, where the player pretends to pass but doesn't. 
The reasons for disallowing this would be if either player obstructed the opposition, which they don't.
If the dummy occurred at a scrum, it is penalised by a free kick under Law 19.38.f.

