Corrected entry: Iggy and Spike say that the portal was closed until someone started blasting it on the Brooklyn side, but Daisy has been on Earth for 20 years.
TedStixon
22nd Oct 2017
Super Mario Bros. (1993)
Correction: The tunnels were already constructed, and it's not too much of a stretch to think that Daisy's mother used the rock to temporarily open the portal (as Daisy herself does).
Correction: The blasting was done by Scappeli.
Correction: In the beginning of the movie, Daisy's mother is seen dropping Daisy off in our world, before running back to the portal through the subway. She then causes a cave-in which kills her and traps Koopa on the other side. This is why the portal was closed until Scapelli started blasting twenty years later.
TedStixon