this is the kind of error humans make because we generate text letter by letter. LLMs generate text in whole words or meaningful fragments of whole words (tokens). unless 1986 is unusually statistically similar to 1968, an LLM is unlikely to make that mistake.

I knew the Titanic was discovered in the mid 80s, but was pretty sure it was not not by this submersible, but a ship pulling a camera. So that took the entire sentence into question and that could IMHO very well been an AI that merged nuclear sub in the 60s and Titanic in the 80s because they were both deep sea operations by this vessel or something.