1. The Gods Are People Too
The core concept of Clash of the Titans - war between men and the Gods - is an interesting one, no matter how poorly conceived and executed in the film itself. The idea that mortals can defy, challenge, and even kill the Gods is an idea that was present in early D&D but has since seemed to fall by the wayside, and more's the pity; if I have one criticism of Planescape as a setting it's the idea that "the powers" will always remain beyond the capacity of the PCs to defeat. (This is incidentally another reason why BECMI is great, and why Planescape would probably work even better with that system than with 2nd edition AD&D.) Having a goal to aim for is part of what adventuring is all about, and what greater goal is there than to cast down the very powers that rule the universe?
(Critical as I am of the Dragonlance line, it must be said that the second trilogy, (the one where the titles all end in "...of the Twins") had quite a compelling theme at its core, what with Raistlin trying to cast down the Gods and become one himself. Pity about the writing.)
A long while ago I wrote the following, which seems germaine:
One of my favourite D&D tropes is the idea that if an individual being gains a group of worshipers, it can attain divinity. This makes religion a very chaotic, ad hoc, and above all tangible thing; unlike in the monotheistic religions of our world where Gods stand aloof, D&D powers' fate is inextricably bound up in the fortunes and vagaries of their followers. It also means the interplay between believer and deity is balanced, with neither having the ultimate power; okay, so High Blierophlat the God of Death can squish any follower he so chooses, but if he does that too often he'll eventually find his disciples running off to some more amiable deity like Jethro the Gardener. Unless of course he's willing to offer some serious compensating benefits.
This approach allows for a much more localised, cultish and fertile religious climate, something akin to how I imagine a trawl through pagan Europe would have been: each group of villages has its own local deity, each cave its shrine to the mountain spirit, each river its sprite, and each boulder its guardian - the major difference being that in a D&D world, those things are real, which is infinitely better. The local village deity really will provide summer rains - if the populace are willing to sacrifice a first born. The mountain spirit will kill travellers with an avalanche unless he is properly placated. The river sprite needs just a few more believers before she can attain demi-goddess hood. The boulder is really a galeb duhr who has had divinity thrust upon him by unwanted worship; all he wishes is that his devoted disciples would just leave him be.
2. Things Don't Have to Make Sense
One of the things (probably the biggest thing) that I disliked about Burton's image of Wonderland was that he seemed to be trying too hard to make Carroll's world have a comprehensible form and function - with a past, a future, a political background and an emotional reality at least vaguely like our own. The Mad Hatter is not the brainless cipher he appears in the book, but an emotionally scarred victim of war; the Queen of Hearts is not the image of passion and blind selfish impulse that she is in the novel, but a scheming dictator aiming for global domination (again with added emotional depth: "It is better to be feared than loved"); the Caterpillar is not a capricious know-it-all but a helpful oracle. Unlike the novels, where there are no rules or logic to either the behaviour of the characters nor the physical world itself, the film has a much more conventional worldview. This is to its detriment - indeed it's what I think M. John Harrison railing at when he talked about "tam[ing], colonis[ing] and putting your cultural mark" on a fantastical setting. (He was wrong about this when it came to Tolkien - whose world was meant to be tamed and colonised by the author himself - but spot on when it comes to Carroll.)
It can be tempting to get worked up over details when you're creating a campaign setting - the need for things to make sense and fit together in a logical and "realistic" way can take over, especially if you're of a certain frame of mind. (Not all DMs worry about things like that, but I think it's fair to say a large portion do.) In fact there's surely nothing wrong with going the whole fantastical hog and letting the imagination and the subconscious run riot, if the players are willing to buy-in; who cares about realistic politics, economics and race relations if you can eat a cake which makes you 100 feet tall and walk through a mirror?