Alright, let's get started!
I think sound wise, you have done an excellent job! Everything done sounds pretty good. There are a few things in the score, however.
For one, the Clarinet NEVER plays in the Alto Clef. I can only barely read it, being a Clarinettist, and I would have never learned how if I didn't study composition. You also left some sixteenth rests in the first complete measure of the Trumpet staff.
There is also a measure on the Piano staff (measure 2) that is a whole rest, but is not centered like the rest. Not only that, but there is a lingering whole rest under the Tubular Bells part... where did THAT come from??
At measure 7, it is unclear to me where the Piano's 8vb marking ends. It looks like the C-sharp, but I think it ends on the A. I cannot tell. While I'm at it, make sure that these lines don't bump into ties and other markings, primarily in the Violin part.
If I were you, I would use different voices for the notes in the Horn, so if voices cross (though they shouldn't), or anything like that, the players can tell which part is theirs. It's just proper etiquette.
Piano dynamics go in
between the staves. Check this out at measure 10.
At measure 16, make sure all Glissando lines look like they "attach" to the ending note. Also, instead of using sixteenth notes, followed by a sixteenth rest and an eighth test, just use a staccato. It's much easier to read and the player will love you for it.
At measure 24, I can see what you are doing in the Snare Drum part, but I think it would be more clear if you didn't have a tie. I almost think a separate, accented hit is worthy.
Measure 26--another place where the woodwinds in particular would love to see some staccato quarter notes. I don't think it's necessary, but I prefer it on a personal level. On the same page you have a colliding Accelerando marking in the Tubular Bells part.
The second-to-last measure has a few comments from me... 1. Why the "Long Fermata?" 2. It needs to be on ALL the parts, regardless of if they have music after or not, and 3. This use of a rest (E of 3) is good--It calls for complete separation.
That is all. I think this sounds pretty neat! I can't wait to hear it with the actual trailer!
Alan