An interesting tidbit about Starcraft 1 is that no enemy unit is ever magically spawned out of nowhere unlike Starcraft 2.
Also in every final Brood War mission there are triggers to give infinite resources (a lump sum whenever their stockpile is low) to at least one opponent ranging from: Brown and Orange as Protoss, Orange only as Terran (as you learned), then everyone as Zerg.
Lastly, there are some interesting unused dialogue in some missions
For instance: in Protoss 6 in the mission briefing originally Raynor and Tassadar talk to each other about the possibility of encountering Kerrigan indicating Raynor was originally playable here, instead it just skips ahead to one single dialogue where Tassadar says he can sense Zeratul nearby and that's it.
As a second example in ProtossX3, Artanis starts by stating that their weapons are ineffective against Cerebrates to which Zeratul replies with his starting line "Remember young templar..." which is why that strange statement is made since he's not addressing you a.k.a. "The Executor".
You are now blinking and breathing manually.
https://i.imgur.com/91NC0Cb.mp4