I follow the channel, can you give me few examples of these errors, as I have not noticed any (I'm not a subject matter expert, or maybe not paying attention enough)

I checked my bookmarks file to see if I had summarized any of their videos there, but if I did, I didn't tag them with the channel name, as I usually do for especially terrible videos. So, unfortunately, to give you examples, I would have to watch another Real Engineering video, which I'm unwilling to do unless someone pays me.

that channel is fine. Obviously, there are errors, especially if you happen to know a certain topic very well. Otherwise, the videos are info are fine for surface-level information.

The video being discussed in this thread started off with a rather contentious claim about the Earth being a giant fission reactor that was heavily debated in the comments. I’m not knowledgeable about the subject at all, but it certainly made me double take (and even open the comments!) and seems to be overstated at best.

The Earth definitely does not produce much heat in its core. Most heat produced in the Earth by fission is produced in the crust. Whether that amounts to "being a giant fission reactor" is a question of semantics; it's like an RTG, but doesn't sustain chain reactions.