Character mistake: When Rose and her friend board the plane, the stewardess offers them champagne. When she hands them their glasses, it is evident that the wine is a non-sparkling white wine, as there are no bubbles rising in the glasses. This is possibly a mistake by the stewardess, but not one that a professional would be likely to make.
Plot hole: During Dream's imprisonment, Roderick Burgess eventually dies right in front of him. That means that at that moment, Death is there to take him away. Why doesn't Death - by far the most responsible and the most sympathetic of his family - see Dream, and let him out? It's completely against the order of all things that he is locked up there, so it's not as if Death can't interfere.
Suggested correction: This is indeed a plot hole for the series. The only explanations are speculation. For instance, Neil Gaiman, talking about the comics, suggested that Death frequently visited the place as various people and animals died. According to him, she assumed that Dream would have asked for help if he wanted it. Another possibility is that the magic was designed to trap Death and somehow became effective in hiding Dream from her. But as you say, for the show, it is a plot hole.
Is this strictly speaking even a correction then? It depends, I suppose, if explanations are allowed for which no evidence is ever seen or heard. I myself don't hold with "what ifs," because they always feel extremely "made up afterwards" to me (although in this case, the post above is very straightforward about it); but it's not my website. Secondly, if Death wasn't able to see Dream (let alone free him), or he her, then wouldn't at least the viewers and the deceased still have seen her?
Not a correction; just an expansion of the idea and agreement that, for the series, this is a plot hole (and for the comic book too, without outside explanation).
As a side note, I think for the graphic novel it might have been just possible to pass it off as subjective camera if we insert the idea that the Endless can't see each other at all due to the incantations (or whatever). But the adaptation has different camera angles, contradicting any attempt to explain it retroactively that way. Of course, it's all "fridge logic" anyway.
Plot hole: The powerful 'amulet of protection' makes the bullets strike the shooters instead of John. Clearly it works not just against magic and other ethereal threats, but also against physical attacks. So why does he almost get knocked over by a car? True, he isn't seriously injured, but he was thrown to the ground. The amulet should have pulverised that car or bounced it at least two blocks away.
