AEA AGMA SM said: "LarryD2 said: "I was working on Broadway at the time, though not on this production, and I recall that Mackintosh and Nunn wanted to bring as much of the London cast over as possible. But Jackman was already committed to The Boy From Oz, and he wasn't going to do two big musicals back to back. In the end, Gabrielle was the only British cast member who transferred -- Hensley did it in London, of course, but he's American."
As I recall Cameron Mackintosh wanted the transfer to happen pretty quickly after their limited run at the Lyceum in the West End. I seem to to remember him trying to claim that to open it as quickly as he wanted it needed a minimal rehearsal period for the Broadway run and that he could only do this by transferring the entire cast from London. Equity understandably fought back and that's a big part of the reason why the revival ultimately didn't open until 2002."
However, it would be doubtful that Hugh Jackman would have been available for the Broadway production had there been an earlier transfer. By fall 1999, he was already filming the first XMen movie ( for which he auditioned while still in the London run of OKLAHOMA!), which gave him his major career break. Before The Boy from Oz, he was busy filming Someone Like You, Kate and Leopold, XMen 2 and Van Helsing.