These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Big Lipped Alligator Moment: In Thunderbirds are GO! the musical number sung by Cliff Richard (Jr.) seems out of place with the rest of the film. Even though it did happen in Alan's dream, it's out of place within that context too.
Harsher in Hindsight: "Terror in New York City" (in which Thunderbird 2 is shot at by an American aircraft carrier who have mistaken it for an enemy aircraft) and "Operation Crash Dive" (featuring planes that end up going off course and end up sinking in water due to engine malfunctions) become harsher to watch after Flight MH370, where the plane went off its scheduled course and crashed into the water, the first of which is never found (and some people suggest the plane was shot down).
Idiot Plot: In the Nintendo (Hard) game based on the show Hood threatens to bombard Earth with meteors in two months unless International Rescue turns the secrets of the Thunderbirds over to him. Ignoring the overkill of this plan, Brains immediately figures out why Hood's deadline is so far away: he needs the intervening time to gather the resources to make good on his threat. And the Tracys immediately discover where he's doing it and work to cut him off. Oops.
The last ten minutes or so of "Danger at Ocean Deep". Scott and John are risking their lives on a ship that will blow up at any second, in the middle of ghastly, thick fog....and then the water around the vessel starts bubbling and heaving.
Some of the "laughing marionette heads" in the opening scene of Thunderbird 6 could also count...
The Hood's eyes glow yellow whenever he uses his psychic powers. It's more than just surreal, it's terrifying.
The rock snakes of Mars will give you nightmares, especially thanks to the music playing. Just listen.
A segment of the "Vault Of Death" score can pretty unsettling, going from quiet to loud and back again, before building up to a loud Last Note Nightmare. The contrast in volume especially dramatic when the score accompanies a scene where an explosive is about to blow open a bank door in said episode. This musical segment is also used in City Of Fire, Brink Of Disaster, Cry Wolf, Danger At Ocean Deep and Path Of Destruction. Give Or Take A Million edits out the dramatic parts at least.
Padding: A positive example to a degree. When Lew Grade insisted that the episodes be hour long ones, the producers had to pad out the time of their first stories already scripted and in production. What they did was add in additional plot twists and character asides such the trope immediately below which gave the stories a great sophistication than what they thought was possible.
Recycled In Space: A lot of concepts were Ripped from the Headlines sixties tropes given a futuristic spin. For example, pirate radio ships being anchored outside national waters became pirate radio spaceships outside Earth orbit, and Concorde became Fireflash.
Visual Effects of Awesome: The vehicle effects were among the best of their time, and still hold up well against modern CG animation (also true for other Gerry Anderson projects). Save for anything involving water, where, much like most miniature work done in water, the scale issues were pretty obvious. Fire, on the other hand, was a series specialty.
Thunderbirds the movie
Ham and Cheese: In the live-action film, Ben Kingsley clearly had fun playing The Hood.
Hilarious in Hindsight: The song "Thunderbirds are Go", which is played during the end credits of the live-action movie, contains the lyrics "don't be mad please, stop the hating". And considering how universally hated the live action movie is by fans of the TV series...