Michael Piller conceived Martus Mazur to be the wayward son of Guinan. Guinan herself was to appear in the episode but Whoopi Goldberg was unavailable. All the references to Guinan were removed and only Martus's status as an El-Aurian was retained.
Oddly, Club Martus appears to be located where the Bajoran temple normally is on the Promenade. The front of the temple had been converted to be a storefront seen in DS9: "Sanctuary". The temple was not restored until three episodes later in "Whispers".
Originally, there were three designs for the probability machine; the handheld device (which was initially designed larger than its appearance in the final episode), the larger device created by Martus, and a four-person gambling orb for the casino. Ultimately, only the first two designs (with some elements from the third) were incorporated into the final production.
One of the ingredients in Quark's sedative drink is "dilithium flavoring extract oz. 435" as shown on Bashir's computer screen. This is one of the many examples of in-jokes that have been added by the show's art department throughout the series.