[mrob]

The motion blur will probably give it away. Accurate video motion blur is computationally expensive but conceptually simple. Just render at about 100 times your target frame rate and average batches of frames together in linear colorspace. You can speed this up by rendering at a lower frame rate (e.g. 10 times your target frame rate), estimating motion, and blurring along the motion vectors before averaging the frames. You can further speed it up by using an adaptive frame rate depending on motion speed and contrast. But a lot of rendered video doesn't even try. Look at a fast-moving bright point of light and you'll easily see the difference.

(But note this is only replicating video, not reality. Truly realistic motion blur requires ultra-high displayed frame rates beyond the capabilities of current hardware.)

[Sohcahtoa82]

A lot of games fake the motion blur so badly. Racing games are often especially guilty.

If you're driving at 200 mph, and there's a car next to you also going 200 mph, it shouldn't be blurry.

Also, the length of the blur should not exceed the distance an object travels on your screen in 1 frame. In other words, if an object moves 30 pixels from one frame to the next, then the blurred image shouldn't be more than 30 pixels wide.