I'm not sure that identifying the ship as the black pearl would really be an assumption -- the facial reactions of Jack and Joshamee fairly clearly imply it.
If that's not enough, then TSH or SoT, could you check if the ultimania talks about the credits scenes at all?"We're werewolves, not swearwolves." (KrytenKoro) 19:33, 18 March 2019 (UTC)