Highlow;
The fact the leading edges appear to be down in the picture, does not mean that the flaps were deployed for TakeOff.
Some observations and a question..
Extension of the slats alone would bring the stall speed down significantly. While the flaps can't be seen in the available photos, the fact that the slats are extended perhaps lends credence to correct extension of the flaps even given your helpful comment re evac procedures and extension of flaps, an interesting if not unfamiliar procedure, and my question is at what point in the Passenger Evacuation Checklist (QRH) is that checked/done and what setting is used? Additional question...are there any WAT circumstances in which a slats-only takeoff is made? - I ask because on the DC9, slats-only takeoffs were employed at high gross weights, (which this flight would certainly not have been). Just curious - not suggesting anything. The recorders will be in good shape.
We can see that the wind, as posted above anyway, was from the aircraft's left (west) side with a crosswind component of between 13kts, (sin50deg x 18kts) to (sin50deg x 38kts) 24kts on the gusts yet, (not particularly significant or unusual
in and of itself), from the photos thus far available, the aircraft appears off the west side of 34R. No overhead photos seem to be available to confirm the site. One report stated that the aircraft was near WC when it departed the runway environment. WC is about 3800+ft from the threshold of 34R. I should think a typical takeoff run would be in the neighbourhood of 4500ft given WAT conditions and headwind.