the explosion of Praxis in TUC (which was also able to instantaneously affect a starship sectors away), the trilithium supernovae in GEN (ditto),
In the case of the Praxis explosion, dialog was [http://www.chakoteya.net/movies/movie6.html
The Undiscovered Country wrote:
VALTANE: Negative, sir. The subspace shockwave originated at bearing three two three, mark seven five. Location. It's Praxis, sir. It's a Klingon moon.
So, that's not a science goof. The shockwave was explained as being FTL.