Wind Whistler: It is illogical to begin a long journey just as the sun is setting.
How did the Sea Ponies survive out of water that long in The Magic Coins?
Molly and Danny were able to find them a little water, but they wouldn't have made if they had to wait much longer. It's not that they need to be submerged in water all the time, but they can't live without coming into contact with some water.
"The Fugitive Flowers" has an Accidental Aesop that counteracts/builds off of its apparently Broken Aesop that, while the ponies did judge the Crabnasties as being the bad guys and the Flories as the good guys because of the former looking nasty, they also did so because the Crabnasties were hostile to begin with, ripping through the forests and refusing to stop and explain themselves. So the episode's aesop is both "you can't judge a book by its cover", but also "Poor Communication Kills" — the ponies were wrong for judging the Crabnasties by their looks, but the Crabnasties were wrong for not trying to be more diplomatic.
"It isn't logical to begin a long journey just as the sun is setting." Of course a flying horse would question the wisdom of Riding into the Sunset (at the end of the day when you're more worn out than you would be if you waited to start until morning, and likely being a waste of work and effort since you probably won't get very far before you have to stop for the night), and of course this question would never occur to a human. Why should a human rider care how long the journey is going to take? It's the horse who does all the work!
In "Bright Lights", Knight Shade's first words are "Knightshade is my name. You say you want to meet me? I say that that's a shame." Given the situation thathe's in with Arabus, those lines are actually a huge bit of Foreshadowing.
During the confrontation with Lavan at the Heart of Ponyland, Lavan mentions that he hadn't gained full control over his power yet, as shown when a barrier that blocked him once before shattered in seconds the second time. If 'cause disasters over an entire country' is what Lavan is capable of at that point, just what would Lavan have been able to do if he'd been at full power?