I would definintely get rid of the green mist and the whole swords thing. It had too many plot holes and didn't work well with the story, I don't think. I did like Will Poulter as Eustace. In fact, he was one of the few things I actually liked about VDT movie. I would not keep the accents for the Telmarines, just as they did in the movie. But other than that, I would change pretty much all of it. The man who played Lord Rhoop, whose name escapes me, was really good even for those few minutes he was actually in the movie, so I would probably keep him.

The big two things I would changed would probably be the undragnoning and the longing of Reepicheep to be a little more obvious.

The undragoning was done in grace in my opinion(but lets not debate about that.) but I hated the timing after Eustace as the Dragon fought the sea serpent. It made the undragoning less graceful and more typical way out by doing a big task.

I liked Reepicheep a lot in the movie, but I wish his longing was a bit more evident at times. Sometimes I felt he was not as excited as he should have been.

Believe it or not, I've been neutral on the green mist for a long time, and still am.

I would add pointless subplots about swords. And any questions that would be raised by changing the story would be answered with "It/he/she was using/is magic."

The Green Mist sub-plot potentially had very good continuity with the previous two Narnia film adaptions, and all the stories are richer for being part of a series.

It was a good adaption addition i thought but it is also representative - to me- of the problems in this area that are there, to different degrees, in the first three films - VODT being the biggest candidate to that by abit of a stretch.

Lion Witch & the Wardrobe was about innocence returning to Narnia via the Pevensies after Jadis's long rule. That's why part of the reason off the bat why the general approach got the general tone & translation right - cause despite a few mid film flatter bits, the more young family aspect of the film was a major part of the books thematic story so not an over whelming turn off to the fantasy family aspect of the narrative.

Prince Caspian has as a major theme a corrupted land in the form of politics & power, almost the opposite emphasis to the super-natural corruption of Jadis/White Witch, this is really the movies core to me & makes it a good fit to LW&W, but dis-appointing to some people who wanted the LW&W story re-told ( abit like how for VODT the makers/marketers tried to emulate the LW&W experience that they had after the perceived failure of PC: in all cases maybe not really getting how the themes of the actual stories correlate to what works or not for the particular films)

The Green Mist for VODT would have worked very well as a more obviously super-natural corrupting influence/antogonist, in contrast to that of PCs, like as was in LW&W, except that it is looking at it from the opposite direction. The Green Mist worked very well cinematically at times during VODT in this kind of way.

These kind of continuities get a really grand set-up in the story themes of Magician's Nephew, which can set up the whole Narnia film series past and present, in a cool way for these type of additional enjoyments for people to watch/absorb in the CoNs.

But this aspect of it's theme was more like a happy coincidence, as the mist was really there for other plot contrivances which i won't get into and which was it's main presence - thus this addition is not well liked when, to me, aspects of it were/are actually pretty darn good..

I don't know. I'd have to change most of the movie to make it a good movie and a good adaptation. The green mist was only one of the huge mistakes made in adapting VDT. I believe it was glumPuddle who summed it up best - Book Problem: Internal (character flaws, sinful nature), Book Solution: External (Aslan)
Movie Problem: External (Green Mist blah, blah, blah), Movie Solution: Internal (the Answer is inside yourself - pure autonomy). Blah.

Hmm - I'd get rid of the Green mist, but I don't know if it would be possible to make a good movie without a real plot - at least we could try! I'd want it more faith based, rather than works - Aslan in it more.
And I'd have Ramandu and Ramandu's daughter- NOT Lilliandil.
And that's pretty much all.

I'd first get rid of the Green Mist Plot altogether. Then I'd put more emphasis on the Lords... make Gael one of the last Lords's daughter. Maybe include some background scenes as Caspian tells the Pensevies about their voyage, such as Miraz sending them off... etc.

Second I'd brush up the dialogue and make it more subtle.

Third I'd add another 30 minutes to the movie including more time in between islands and more time exploring the islands.

Fourth I'd give Aslan a bigger role, change the undragoning a bit, and reinsert the scene with Aslan, Lucy, and Coriakin, as well as the lamb scene (it wouldn't even have to be CGI I wouldn't make it talk.)

Fifth I'd make the sea serpent scene separate from the Dark Island.

Sixth if I don't eliminate it all together, I'd reduce the WW's scenes to one in the Dark Island... and neither she nor Peter and Susan would appear in the promotionals

Seventh I'd focus the advertising on the story itself and not on the fact that it's a Narnia movie

Re Alsan 'wolfloversk':

I too would have him on the Magicians Island with Coriakin, and haved him giving the backstory there relating to Coriakin & the Dufflepods because it's a wonderfull backstory & also because part of VODT's charm is in it's adventure of discovering the wider fabric to Narnia.

I also would have had Aslan set up for Lucy, that a deception is going to happen for her in the voyage ( as i would have amplified this theme as the films major thread) & that things will be different in the uncharted seas of Narnia including himself-Aslan (re my first post with what my story change for what this is generally & including the Green Mist which i liked in concept).

I found Aslan to be heavy handed in the film, & for example with my adaptions of the adaption, am trying to do the same things with Aslan in a more subtle & resonating story way.

I didn't like the Lucy/Georgia Henley character arc in VODT and also thought it was a waste of her acting talent - i mean, for the climatic payoff to this arc it doesn't even involve Georgia Henley in the scene, it's Susan as Lucy! I wish they had watched Prince Caspian more closely and see what a great young actress they had with which to branch out with for VODT in a series trade mark kind of fashion. She could have been successfully used to give the film both more depth & general accessibility to it's main potential themes, as through the film she still manages to pull off a great Lucy with a rather bland written character at times.