Other mistake: Beethoven didn't seem fussed nor resentful of Napoleon being part of the group. Historically he temporarily admired him and wrote the Third Symphony inspired by Napoleon's ideals of Europe's new hope of enlightenment but later despised him after he crowned himself Emperor of France in 1804 and furiously scribbled out his name off the title page of his Third Symphony and named it Eroica which he originally titled it as "Bonaparte Symphony" due to his former admiration of Napoleon.
Other mistake: At the Circle K when future Bill and Ted have finished talking to present Bill and Ted and go back into the phone booth, where are the other 5 historical figures? Especially as it is emphasized that they are all squished together, when they land you can see Beethoven, but he isn't there at the end when they leave.
Answer: Yes and no. The basic premises are all right; the years are accurate, and maybe the costumes. Napoleon was at war in 1805, and Joan of Arc was undoubtedly in church at some time during 1429, etc. But everything with the mysterious King Henry and his two teenage daughters in the middle ages is completely fabricated. Although there were four King Henrys during that century, none of them fit the age or family situation seen in the film.
Krista