So I thought I'd take a look at the opposite, a few examples of errors in the original printings which they belated corrected in reprints decades later.
Back in 1973, Jack Kirby was wrapping up THE DEMON, on the 15th and penultimate issue he and inker/letterer Mike Royer used what was then a not unheard of but not terribly common effect of some solid colour lettering, with no black border (like the aforementioned DCCP issue did for the Word of God). The New York offices apparently couldn't handle it any better than the Brits could in 1983. So readers were left to wait the inexplicable 36 years it took DC to finally reprint the issue in 2009 before they found out what the Klarion was exclaiming.
You do have to deal with DC's odd choice to eliminate the cover price from cover reprints. Don't like that on issues where the price is so large, throws off the balance of the cover.
Jumping ahead to 1983, and LEGION OF SUPER-HEROES #302 artist Keith Giffen decided to save a few minutes and achieve an interesting visual effect by asking the production department to copy and enlarge a panel from the previous page a few times. His note to that effect might have been a bit too subtle, so we readers got a backstage look at comic production, sort of like a boom mike coming into frame on a TV show. Only took 28 years for the first reprint of the story in 2011 to come out, allowing DC's crack production team to finish the job.
And apparently there might be a Curse of Etrigan, because in 1987 Matt Wagner and Art Nichols revived the Jack Kirby creation, and in THE DEMON #1 there was a plot point about an old book that Glenda Mark had with a drawing of a demon named Belial who resembles Etrigan. But we're shown a blank book. Never seemed quite right, but at the same time a plot point is that Jason Blood can't see the resemblance, so maybe it was meant to be blank? Well, this took only 27 years, but goof was seemingly confirmed in the reprint.
Interestingly, they also corrected the amusing error on the cover to #2, which prematurely announced it was the last issue of the mini-series.
There are a few more examples, if I remember exactly where they were I'll update, or feel free to add any you know of in the comments. No need to limit it to DC.
But this one is from DC. In 1975 DC published an ambitious tabloid sized volume of Old Testament biblical tales from Sheldon Mayer, Nestor Redondo and Joe Kubert. The big mistake is that they never published another volume, despite considerable work being done a second book of "The Story of Jesus". But in addition to that, there's something off about the cover:
Apparently whoever coloured it was under the impression that Moses was going to auditioning for the Blue Man Group right after coming down the mountain. I'm sure Joe Kubert flipped at seeing that, exclaiming "The Blue Man Group won't even exist for another decade, so they're definitely an anachronism in a Bible story! And they would never hire someone with that hair". Took 37 years, but that fatal error was corrected in the 2012 hardcover reprint.
Here's one not from DC/ LARRY MARDER'S BEANWORLD - HOKA HOKA BURB'L BURB'L [2017] was doing along swimmingly when, on page 146, something happened that's strange even for a book called Beanworld, when Proffy vanishes for a panel while discovering something about Bean life.
Creator Larry Marder discusses the reason for the mistake over here, and it was subsequently fixed in digital versions and in LARRY MARDER'S BEANWORLD OMNIBUS #2 [2019].
