Deep Space Nine - Trials and Tribble-ations

Plot: In a Forest Gump type manner, the DS9 cast go back to in time to keep a Klingon spy (Darvin from the TOS episode the Trouble with Tribbles) from changing history by planting a bomb in a tribble.

A fun and clever episode that dresses the DS9 gang in TOS Star Fleet uniforms, and intergrates them with footage from the TOS episode. For example. during the TOS bar-fight with Scottie and Checkov, Worf,  O'Brien and Bashir all get involved, and end up  standing among the line of officers Kirk questions.

Funniest Moment:  Worf tries to explain why TOS Klingons look nothing like DS9 Klingons:  "We do not discuss that with outsiders" 

Summary: The only thing wrong with the episode is its absurdly high rating (9.2).  Its a fun and nostalgic - but nothing more then that.  "Fan Service" to the extreme.  Further, it highlights the lack of charisma in the DS9 actors.  Sisko, Dax, Bashir, and O'brien - in particular - look bad in comparison to Kirk, Spock, McCoy, and Scottie.