- Recurring characters.
Movies in general get away with this better than multi season shows with actors contracts and killing off a character early.
Sean Bean humourously being killed off in LOTR and Game of Thrones. This also ties into later seasons when the writers were afraid to kill lead characters. Jack Reacher does well not bringing back 2 of the leads from season 1.
Foundation is deathly afraid of this, having 6 characters that carry over season to season where in the books there are none.
- Faithfulness to source material.
For people who have not read the books, Dune part 2 does end with a white saviour story and includes holy war, religious imagery. The distance from 9/11 helps though the middle eastern conflicts don't. A few actions scenes and techy stuff is added and some ideas and scenes are moved around. The daringness to commit to the source material is amazing, weird worm bile, talking babies, drugs and hallucinations
Foundation ignores this, having pacifist characters shoot at each other, adding pointless sex and action scenes that have no impact on the plot. The core premise abandoned very early on. It's like they wanted to make their own sci fi show but just slapped the name on it
I remember Asimov's books in the Robots/Foundation universe to be fairly coherent. Newer books revealed new things that weren't alluded to in previous books, but they didn't break continuity.
The only inconsistency I can think of is how the pre-Foundation's Edge books didn't feature the computers we then saw starting with that book, but it's not like the older books specifically stated they weren't there.
And if all else fails, you can always explain anything by bringing The End of Eternity into the canon 😛
I remember some really jarring inconsistencies between the robots of dawn and the previous two Elija Bailey books. It really seemed like Asimov didn’t even bother to read his previous books before writing The Robots of Dawn. There were several inconsistencies.
One big one that I remember is that in The Robots of Dawn City residents have salaries and money! Previous books were explicit that there wasn’t money and instead people were given allotments of things based on their position in society. This is a huge change and it’s not acknowledge at all. It’s treated like it’s totally normal to have money in The Robots of Dawn.
Some other differences were smaller, but still made it obvious that Asimov hadn’t read his previous books before writing new ones. For example, Bailey is comforted by the night sky in The Robots of Dawn where in previous books, the night sky made him more disoriented and made him pass out because he could see out into space. It wasn’t meant to show that Bailey had progressed. It was presented as an obvious fact that people of earth would feel more comforted by night skies. There were a lot of small things like this.