To avoid this as much as possible you will need to turn down in camera sharpening all the way, or shoot ever so slightly out of focus.
What is shooting ever so slightly out of focus? Shooting with something else in focus? So where is the viewers attention going to be drawn to? Away from your intended 'slightly out of focus' subject, that's for sure.
And once focus is out it is very hard to put it back in. With large sensor cameras it is imperitive to nail focus. Especially as they are potentially going to be shown on large to very large HD LCD's etc.
I don't know where you picked up this kernal of advice, but you should never ever repeat it ever again.OP.
1. Shoot in focus.
2. Advice to reduce in-camera sharpening is good.
3. You can get mirrorbox insert filters which help to combat aliasing, although they are cumbersome to use and expensive.
4. The 5D3 is probably the best sorted DSLR for video at the moment, but that isn't very helpful as you are already shooting with an alternative, and besides, not everybody can afford such an expensive camera, don't be fooled that the 5D3 is moire proof.. no camera is.
5. You can fix 98% of bad moire and aliasing in post, I'll now go into some detail how.
You are making a short film so I am going to assume you are going to be doing some editing. I don't know your level of competancy with any particular suite, or your technical knowledge of video in general, unfortunately it is fairly technical and dry, I'll try and be as straightforward as possible, if you need any elaboration at all, please ask here, or PM me.
I use legacy Final Cut and Premiere, I'm going to speak in legacy final cut terms, which should be largely interchangable with your suites terminology.
FOR ALL your footage: make sure it is interpreted or transcoded as progressive.
YOUR SEQUENCE: use a progressive codec.
OUTPUT: Make sure you take control of any further encoding be it to H264 for web or MPEG for Blu-ray or DVD, where the option exists keep it progressive.
Mismatches between interlaced and progressive can introduce aliasing where there was none, and make any pre-existing aliasing 10x worse. So keep it progressive as far as you are able from shoot to capture to edit to output.
I am in the habit of putting a blanket .5 pixel guassian blur over my timeline. If a particular shot has really bad aliasing I may go to .75 or even a full pixel for that particular shot. It's a funny thing, that .5 isn't really noticed except by it's absence. it won't make your footage soft, just a bit less 'video'.
Where there are zones of pronounced aliasing or moire I will create a duplicate upper layer and heavily apply MarvelsDSLR filtering and sometimes a heavier hand of guassian blur (maybe 1.5px) I would then garbage matte around the affected area with a feathered edge so that the unaffected areas can still be used.
Please please please don't ever shoot intentionally slightly out of focus, what is slight on a 3" LCD can be horrific on a 40" tv.