Can I move to mortgaged property when rolling 'Mr Monopoly' on Speed Die
From the rules here

From mortgaged properties rules.


  If the property is mortgaged, no rent can be collected.


From the speed dice rules -


  If you roll a Mr. Monopoly after all of the properties are owned, make
  a normal move according to the white dice, then move ahead to the
  first property on which you need to pay rent. If all other players
  properties are mortgaged, stay where you are.


Together, these rules mean that the first property on which you need to pay rent cannot be a mortgaged property.  You must therefore move to the next non-mortgaged property owned by another player, in order to pay rent.  The rules also clarify that you don't move if all other players' owned properties are mortgaged, which is further evidence that you cannot move to a mortgaged property when you roll Mr. Monopoly.