This is one of those situations where I'd rule against the RAW. You and your illusionary selves are recklessly attacking and putting no defense effort in to protect yourselves. If the illusions are less reckless than you, then you are easy to identify and target. I'd have the advantage apply to you and the illusions.
What exactly is "putting no defense effort in to protect yourself" in the rules though?
That is a "made up" phrase that is often used in D&D discussions to try to explain rules. Or to try to explain why a rule should be changed in xyz scenario.
So, if my PC is prone and my images are prone, prone applies to the images? It might seem obvious, but it's not a simple answer.
Do Major Images of a prone creature get prone disadvantage bonus versus ranged attacks if a target attacks them? If so, why does an image of a creature get a prone disadvantage vs. ranged whereas an image of a rolling pot (same overall relative size or even smaller from attackers point of view) does not?
How about Blur? Are the images blurred too and foes get disadvantage against them? If one combines Blur with Mirror Image, do the Mirror Image spells get more powerful and useful?
As mentioned earlier by Hemlock, Mirror Image is just plain messed up as a spell. It should convince targets that any of the targets are real, hence, any type of attack and defense should apply the same (i.e. which image do you target with Hold Person?) and all of the normal rules should apply as if they were creatures. The power of Mirror Image should be in the fact that it is an illusion and foes do not know which image to grapple, shove, swing a sword at, or cast any spell at. The image should have all of the defenses of the PC, abet lower (like lower AC, lower bonuses to save and ability checks, etc.) and practically any type of attack action or offensive spell (except area effects) should be able to pop one of them. That being the case, then yes, advantage and disadvantage would apply as if it were the PC and Magic Missile could wipe them all out with a single spell. But without those types of corrections to Mirror Image, cherry picking which effects (yes to Reckless Attack, no to Blur/Haste) seems overly subjective.
As a matter of personal taste (on the subject of prone), I have never understood why archers get disadvantage on prone foes. That rule does not make sense. The foe is moving around less (a lot less mobility than standing) and should be easier to hit, even if it might be a slightly smaller target (if head or feet are facing the archer), or basically the same size if the target is perpendicular to the archer.
