I posted this in the Day 4 thread:
Watched the race on freeze-frame several times now. Contact definitely was between Martinez and Wilson at 1:34.8. I just can't see EXACTLY what happened because the pause gets a little blurry. Wilson does not react to the contact at all. Looks like Wilson's right leg was back while Martinez's left leg was forward and that's where contact occurred. Definitely no initial contact between Martinez and Montano.
Martinez pops up with arms flailing at 1:35.4. First contact between Martinez and Montano at 1:36.0. Montano stumbling at 1:36.3. Ludlow looks affected by 1:36.5. By 1:36.8, Martinez is in lane 3 and Montano looks to be falling.
1:37.5 Montano is nearly upside down, Martinez looks like she is being struck by Montano as she has a grimace on her face and her body is in a weird position. Ludlow still looks OK. 1:37.9 Montano is on ground and Ludlow has stepped over her. Martinez is stumbling into a more outside lane. By 1:38.2 Wilson, Rogers, Grace and Ludlow are all clear of Montano and Martinez is in what looks like Lane 4.