This is the link to order tickets provided by MBF for "MBF members" but I went today with the family and they didn't question a thing, they only asked to confirm the last few numbers of the credit card on my printed A4 Eticket. A few excuses i had ready were "I don't carry the card with me." OR "I only bought my credit card and mobile with me." The conditions below do not state they require you to show your membership card.
Online Ticket Purchase
Dreamworld does not post out any of the online tickets, except for the Gift Certificates. Entry to Dreamworld is granted by presenting the printed E-Ticket sent to your email address, the credit card used to make the purchase and photo ID on arrival. If the credit card used for purchase is unavailable, another credit card must be provided for security. Internet ticket bookings must be completed a minimum of 1 hour prior to entry to the park.