I've never believed that each cube has a Queen; that would be a little silly. Remember her rejoinder, in reaction to Picard's confusion, when he said "But that ship was destroyed": she said, "You think in such three-dimensional terms. How small you've become." There's a more complicated answer here. William Shatner speculated in his written sequel to Generations, "The Return", that the Borg have the ability to move in, and control, a fifth dimension of space, and that it gives them power and understanding that other creatures lack. I think she just shifted herself out of that ship, that perhaps, as the collective personified, she has the ability to move instantaneously (electronically? perhaps her form, her body, is from a mold that's recreated wherever she moves; remember, she once said in Voyager, that she was a member of a species herself; 135, was it?).