 Charlie Brill returned to film new scenes as Klingon agent Arne Darvin , while original series writer Gerrold was allowed to appear as an extra in two scenes as a crewman from the Enterprise . In one of those scenes he was holding an original tribble from " The Trouble with Tribbles " . Walter Koenig was on hand as well during the filming of the episode to teach the DS9 actors how the consoles were operated on the Enterprise . Koenig later commented that he was paid eight times as much for this and the residual payment as he had been for the original episode . A string of other visitors came to the set during filming , including Majel Barrett and former The Next Generation producer ( and <unk> co @-@ producer ) Bob <unk> . 
