Found this review on the net:
Note that this “Extended Cut” of The Missing adds about 17 minutes to the running time of the original theatrical version. I’d love to detail all the new segments, but even though I saw The Missing twice before I got this new DVD, I found it hard to recognize the extra footage.
I can identify three added pieces because Howard mentions them in his commentary. In one, Jones shoots a mountain lion, and another shows a confrontation with a tarantula. We also see a scene in which Maggie teaches Dot to kill.
Though I’m less sure, I think the other reinstated segments deal with various character issues. For instance, we find out more about Jones’ past and get some expansion of his relationship with Maggie and the others. These add a little character definition.
But not enough to rescue the movie, unfortunately. The extra length of the film counteracts whatever greater depth they may add. I thought the 137-minute version was too long, so a 154-minute edition becomes downright painful. The 24 people who liked The Missing may get something from this extended cut, but I didn’t.
Enough said, I suppose.