I would reword your points thus:

1. I would replace "scene", (a scene is a mental representation). The retinal image containing photons reflected from objects in front of your eyes receives additional illumination during a flash. The photons cause electrical impulses that create successive waves of activation of the visual cortex at periods from about 10 ms onwards, relatively peaking at 100ms and 300ms.

2. I would be accurate about the cortical ERP: The additional illumination gives rise to an event related potential in the visual cortex from about 10ms to 700ms post flash.

3.  A specific event cannot occur twice in a four dimensional spacetime (it may well be able to in 3D or nD). In fact this is the entire argument about time-lags: the universe is 4D therefore the same event cannot be at two separate times.

4. See 3

5. See 3. I do not agree that we can blithely use the term "mental representation" in the context of Event Related Potentials.  A mental representation containing a flash is not a set of electrical pulses occurring over about 700 ms, it must be something else.

What do you mean by "mental representation"?  I would describe it as a projective geometry formed by the concurrent and simultaneous events in my experience.  Is that what you meant?