According to makeup supervisor Michael Westmore, the love scene in this episode between Lang and Quark is one of his all-time favorite Star Trek scenes due to the fact that despite all the heavy makeup, it is still just a touching, simple romantic scene between two people in love, and the makeup becomes completely unimportant.
During filming of "Profit and Loss," a 6.7 magnitude earthquake struck along the Northridge fault in Southern California, including the Paramount studios where Deep Space Nine was being produced. The earthquake struck on 17 January 1994 at 4:31 AM, when Armin Shimerman, Mary Crosby, and other actors requiring extensive makeup were having their makeup applied in preparation for crew call at 5 AM. Most of the actors in the makeup trailer ran to their cars and drove home to check on family members. However, they were still wearing their makeup. Filming resumed on 19 January - albeit amidst a series of aftershocks.
The original teleplay for this episode very closely paralleled the plot of the 1942 Academy Award-winning Michael Curtiz film Casablanca. In fact, it was originally called "Here's Lookin' at You...", a reference to a popular quote from the film. (AOL chat, 1997) The producers however, were forced to change some of the more obvious references to the film as well as the title when they were threatened with legal action.
Armin Shimerman and Mary Crosby's makeup had to be touched up each time the actors kissed, since his orange makeup would end up mixing with her gray makeup.
Mary Crosby, once famous for her role as the woman who shot J.R. Ewing in Dallas, is the daughter of Bing Crosby, and aunt of Denise Crosby, who played Natasha Yar on Star Trek: The Next Generation.