Ok, so this post from https://mstdn.social/@SeanAloysiusOBrien@tenforward.social (and subsequent replies from https://mstdn.social/@Taweret@octodon.social et al.) got me thinking: What are the Star Trek Extended Universe versions of Chekhov's Gun?*

https://tenforward.social/@SeanAloysiusOBrien/110794351529449709

Off the top of my head we've got:
nebulae
terraforming/colonization/et al.
experiment
warp drive modification
novae/supernovae
treaty negotiations

Any I've missed?

*All puns intended. Deal. With. It.

#StarTrek #STTOS #STTNG #STDS9 #STSNW #STBD #STP