Flashback is the final Ingredient of the Scene. The first question to ask whenever using a flashback is: Why is this character having the flashback to this particular time?
Was it a life-changing moment for the knight at the top of the page? Was he wounded in battle? Has his horse thrown him? Or is he an old man thinking back to this moment and all that came after it?
Or perhaps the cloaked woman with the sword is your Point of View character, and the knight on the ground is from her flashback.
Will the plot be affected because of what she's remembering? It should be.