"zero hour" features several guest stars. los angeles actor david kaufman was brought in to play the part of mark gilmor, a red herring to the story. cliff simon, flown in from l.a. for a day's work, filmed most of his scenes as ba'al against green-screen in the gateroom for a "hologram feel". bill dow (dr. lee) was doing theater work in vancouver during the filming of this episode, necessitating the producers to schedule around his availability. gary jones's character, an "sg-1" semi-regular technician who sported the name "norman davis" on his uniform for years, received a new name in this episode: "walter harriman". after o'neill had referred to him as "walter" in the season 4 episode "2010", the producers could not get clearance for a renaming into "walter davis". the new name is based on general hammond referring to jones's character as "airman" (sounding like "harriman") in the pilot episode, and "sg-1" writer joseph mallozzi explained the resulting incongruity as a married-name issue. one scene in "zero hour" features pierre bernard, a graphic designer for the nbc show "late night with conan o'brien", as technician o'brien. the "sg-1" producers saw bernard ranting on "late night" about "stargate sg-1" being better without daniel jackson (actor michael shanks was not part of "sg-1" during season 6), and gave him a cameo spot.