I have gotten a mild version of this, and have read posts hear by PTSD folks having really strong experiences of this. So you are not alone.

For me, I just let it wash over me, like I am listening to the radio or watching tv. If I don't try to suppress it, it sort of runs its course and fades.

Flashbacks can have pictures to them, so you see the trauma happening again, The memory is extremely vivid. But as Jen said, for me I can tell the difference between a flashback and hallucination. With flashbacks I still know who I am and where I am in reality even if quite terrified and remembering. The few times I've hallucinated, I had a very high fever and I did not know I was hallucinating, I thought it was reality. Then with Multiple Personalities, I hear voices in my head of people talking who are not me. This is different than the first two also.

My flashbacks come with sensory feedback. I was in riots with gunshots, buses and cars turned over and burned, so I can smell the burning cars during a flashback at times. They say that, of the 5 senses, smell is the most connected to memory in the brain.

Other times, an image comes with a flashback, too, as someone else said here.

I wouldn't think these qualify as hallucinations, but as sensory information from the past "leaking" into the present, as Kurt Vonnegut wrote about his World War II memories from being a prisoner of war.

In any case, they can intrude on the present and on tasks like trying to go to sleep, so in the end the difference can be academic. You listen to music. As I go to sleep I tend to listen to a standup comedian, just to go to sleep with a chuckle and a smile. What works is what matters.

I think it might even be "normal." When I was actively repressing memories, they kept leaking out. I repressed to an extent that they leaked any hour of the day or night.

During the years of learning to sit comfortably with my memories and simply observe them I have come to believe that memory includes full sensory recall. When I do not repress the process it can happen so quickly that there is no conscious recognition of anything but the summary under which it is filed in my cognitive memory. Kinda like when someone tells me to "sit" and my body remembers all the electro-chemical and muscle processes of how to sit without cluttering my conscious all those details. Look it up. There are quite allot of physical subroutines in the "simple" routine of sitting.

What is "abnormal" is the drive to repress.

yes you get sensory recall, one problem is people keep making you relive things. i get that with sex stuff, they keep going thru this that
and it just reinforces the recall so it gets worse again like a torture tactic
but its all quite real, but the effect is to mae you live it for hours
instead of a few minutes in the first place at times so it feels very sore
in youre head at times after. so obviously it happened or it wouldt be there, so its not exactly hallucinating if theres any break through
it like involuntary replay or recal i think.