Things that don't make sense

I never realized this. You just added 2 more plot holes to this movie

There's a lot in the Star Wars universe from beginning to end that doesn't make perfect sense. These are fine examples.

However, I need to bang out some clarification on this misconception: "And how can the speeders have a problem with the cold? They can build ships that travel through space which is much colder than a planet with an atmosphere and allowable breathing."

While true that there is no heat energy in space, it's also a vacuum. A vacuum is the best insulator there is. There is no conduction or convection to remove heat, which leaves just heat energy escaping though radiation, which would be reflected back internally by metal and glass.

Being in ship in the vacuum of space is literally like being in a vacuum thermos or double walled stainless steel Yeti cup.

The thing is, even though it's called "Star Wars", I don't think Lucas really knows that much about war.

It's still a fun ride but it lacks sophistication in some departments.

My guesses:

1: Luke was going stir crazy in the cave base, so he ordered some low-ranking scout to give up his assignment and tauntaun, without realizing how dangerous the job was. Because as we all know, Luke is a bit dim, and knows diddly-squat about ice ecosystems.

2: They only had a couple of big guns capable of taking out the biggest AT-ATs, and those guns had to be pointed upwards at the enemy spaceships. If they could only be used to clear passage for the transport ships, then presumably they couldn't be quickly moved 90 degrees to also shoot at the AT-ATs, and Leia had to choose whether to use them to clear passage for the transports or shoot at the AT-ATs.

Also, presumably, those huge anti-spaceship guns were left behind.

While stuck inside the giant earthworm, Han gets the heebie jeebies and decides to test his location by firing a laser blast on the ground causing the "cave" to earthquake.

But when flying into the worms mouth wouldn't the heat from the engine of the Millenium Falcon do the same thing? Shouldn't it have been spitting out the falcon? if heat hurts it, shouldn't the worm be kind of happy the falcon is leaving? Where do these bats come from? Wouldn't the worm digest the bats too?

1) I heard the line "we're having trouble adapting them to the cold" many times but never thought of it much. Maybe the speeders are not like X-Wings and are not built for space travel/combat? But yes, having Luke outside by himself without some kind of escort is crazy, he's probably the most wanted man in the Empire at that point!

As for 2), I noticed the scenes where we see the speeder POVs and we see Rebels running around like ants in the snow amidst the chaos, and since they're not in the trenches with the weapons, it would be easy for the walkers to pick them off one by one.

Han solo and the gang being chased in the Falcon. The Star Destroyer is gaining and they can't go to Hyperspace.

So they turn around and attach the SD.

"Shields up" says the Empire's Admiral.

But notice how Han pulls off his little trick... he attaches himself to the back of one of those Star Destroyer towers and turns the lights off.

Only thing is once the shields are up how can he get anywhere close to touching a Star Destroyer. Isn't that the whole point of shields? Also, no tie fighters with lights flying around to look?

For the speeders thing. Maybe the speeders have already scouted the area and found no life or droid activity? It's not as if they have just arrived there when the movie begins, they've been there a while. As for freezing speeders. Possibly because frost, ice and snow tend to accumulate on things and could freeze/jam moving parts unlike in space?