We’ve all been there 
I usually will only go back if there’s a mistake in the text. For all else I just move on. However it’s important to take a through last look at your pages before you submit!
one of the problems i have is missing typos. no matter how many times you have looked at the page you seem to miss a typo until it's posted. I have learn't over the years thee is a difference to reading a page and know what it should say so skimming over it.
All the time, I even really simplified my character designs for my comic so I have no excuse to forget the few details they have on them.
Thankfully with digital releases I can always go back and fix stuff I forget... at least when I have time... there's still a panel a few chapters back where I forgot to draw a beard on one of the characters and didn't realize until a few days ago. Eventually I'll fix it.
Would be nice to have an editor that checks for stuff like that before release. The indi life man... x.x
I forgot about a detail from the very first page of my comic but decided to move on. I usually take this approach to mistakes, unless I forget about some really important detail or it's text related. I'm not a native English speaker and I also do a lot of typos no matter the language I write in, so stuff like this happen... xD
I do go back to fix it. I tend to forget the color of the stuff in the backgrounds. XD Like make the sofa blue instead of purple. And I know people will notice so I chose to fix it. But honestly when other authors miss details I personally don't care and I don't point it out.
I just constantly use the preview tool and keep noticing small mistakes and then have to go back and fix them, so then I can see the NEXT mistake. I don't think there's anything wrong with going back to fix things if it makes you feel better, but if it doesn't and its not confusing to the plot I don't think most people will care.
I think this is something everyone does, it's easy to get hyper focused on certain elements of a drawing so I wouldn't call it a stupid mistake! It might help to have someone look over things before you submit it, or sleep on it and then review it again.
If its a huge mistake, then it has to be fixed. If its a one panel thing, I'll just move on.
Drawing or coloring on the wrong layer for 20 minutes is my most common mistake.
Thank you for making the forum topic. Sometimes I make up explanations to make the mistake a valid part of the story. Here are some examples of what I mean.
If I make something the wrong color in one panel, I might say that the lighting from that angle made the person or thing appear to be that color.
If I forget to draw in one panel the tail of a warrior that is in battle, I might say that the warrior has the ability to retract their tail and does it sometimes as a strategy.
If I forget to draw in one panel the battle wounds of one minor character is in battle, I might just give them the ability to regenerate.
I try to correct as many typos as possible and if I don't get the dimensions of people and objects correct I leave it in. I just make a mental note to try to not make the same mistake in the future.
It depends. Usually little visual things like that I'll go back and fix, since my readers tend to notice those sorts of things -- so like, I have one character who lost a finger, and it was kind of a big deal when he lost it. I occasionally forget and draw him with all ten fingers, and if I notice this, I'll go back and fix it, because that's the sort of thing where if a reader noticed it they might wonder if he regrew the finger or faked losing it or something, and wonder if there were some magical shenanigans going on.
I have another character who wears a necklace. The necklace isn't important to the plot and has never been mentioned, it's just part of her outfit. If I forget to draw it in a panel or something.... I'd probably just leave that alone. Or I might eventually fix it for the book.
Generally, though, stuff like that isn't super important. It's amazing how you can establish that a character has a gun, forget to draw the gun for the next 20 pages, and then have them shoot the gun in a crucial moment, and most folks won't notice because you already established earlier that they had it. Some friends and I once cosplayed another friend's webcomic characters and SUDDENLY noticed hundreds of little things like this -- tiny outfit changes and inconsistencies and drifting/changing details from page to page, and the thing is, we literally never noticed any of these until we were sitting down to actually cosplay the characters. Prior to that? It had never mattered.
So it depends a little bit on how many clues you tend to hide in small details like that, but other than that, it's really up to you whether it's worth it to you to go back. Most of your readers won't really notice.
Depending on how big of a mistake it is, I'll either leave it and hope too many people don't notice or change it. Most of the mistakes I've made in my story were missing colors/white spots I missed during the coloring process. I think another mistake I make during the coloring process is coloring on the wrong layer in Photoshop (ie. coloring the hair on the skin layer or the clothes on the background colors layer by accident.
If it's a spelling mistake I'll correct it straight away, even if I've published it. Because I'm fussy with spelling.
But if it's a drawing mistake, I can't really be bothered lol, I forgot to draw a pocket on a shirt on my first page, and couldn't be bothered to correct it lol
Usually I only notice these mistakes, when I'm coloring. Most of the times I forget jewelry, and gloves. These times I try to draw them in Photoshop. I can only hope that only I can see the difference 
Sadly I have bigger mistakes too. I was always bad at drawing hands, and sometimes... I switch fingers!
And my other favourite is when I don't remember well the background. I try to get back to the right pages to copy them, but sometimes I do mistakes.
I thought this page is talking about me.
I know the struggle especially in more complex design of a character (which I have a lot, but I don't draw comic anyway). To solve this usually I:
1. Practiced to draw the character beforehand repeatedly, so I can memorize it beyond head. make a clear reference.
2. Always compare, always check with reference in each step (sketching, inking, coloring, finishing, submitting)
3. If mistake detected, fix them ASAP because you might forget it.
4. You can always fix it later even after submitting, readers often have sharper eyes
In general I go back an fix it, unless it's a minor or non relevant detail.
Another way is to incorporate that mistake into the comic. For example, I drew a background character that was arm crossed and accidentally colored his hand with the color of the shirt, I edited that panel once or twice because of other mistakes and didn't realize about that hand. When I finally saw it, rather than change it (because I was tired of editing that particular panel), I decided to leave him as "Jimmy Greenhand" and maybe give him some appearances as a side character.
Currently I have again a stupid mistake problem. In the chapter I am working on, my heroine has a pocket mirror in her hand.
And she starts to chasing the villain.
They end up on a stage, and for stop the villain, she gets a microphone in her hand, and catch the villain with her other hand.
The problem: I forgot about the mirror!!
How would you solve this problem? My husband said that it doesn't matter, because with reading the readers would not care about where the mirror is. But I am still worrying. What do you think?
Is she going to need the mirror again soon? Do you need to include it in her hand in the first place? If it's a plant for a payoff later you should be conscious of it because you want your readers to notice it too, but if it's not relevant to the story it doesn't matter.
The villain was trapped in the mirror, but she could came back now because the heroine lost the mirror the last time they met. The mirror has the power to gain wishes, and before the chasing scene, the villain gave the mirror to the heroine to tempt her for wish something. After this scene it won't have more role in the story, but once they already forgot about the mirror, so it is kinda funny that it happens again 
Now that I think about it, maybe it can be solved with an extra funny scene...
Good luck!
