Now! Let's start with this, shall we?
Mr Mytton's imagined railing:

The actual railing:

Mr Mytton's gone and put the lady in black on the wrong side of the railing! 
F for fail!
Now #2! We see this lady in black, who is on the
east side of the center railing,
twice in Mr Mytton's final gif frame:

She must have climbed over the railing between Wiegman and Darnell!

Either that or poor panicked Mr Mytton has gotten his overlay badly wrong...
"I, Mr John Mytton, believe the dark vertical strip down Mr Lovelady in Wiegman has a simple rational explanation: the front entranceway changed shape dramatically during the shooting."
