Looks like the filming was "additional" filming and not reshoots:
We know that, at least part of it, was filmed in LA. Also, just checked
Scott Derickson's twitter feed and his latest tweets all have the LA/LA area location stamp.
As Amanda mentioned before, maybe this could explain Rachel spending so much time in LA lately. Although, Wong was involved and I don't think it's likely his character's path will cross Rachel's but I guess you never know
