 Recycled footage from the original series episode "The Trouble with Tribbles" is used extensively in "Deep Space Nine"s time-travel episode "Trials and Tribble-ations".In addition to extensive archival footage of cast from the original series, actor Charlie Brill (portraying Klingon spy Arne Darvin) appears in both new and archival footage.The episode was designed to coincide with the 30th anniversary of the original series.