Treshure planet
The 13th Warrior, I don’t know if it was a flop but it came out when something big like Lord of the Rings came out so just got overshadowed.
Idiocracy originally tanked but it’s a great movie and made a huge comeback a few years later
Willy Wonka and the Chocolate Factory did so-so when it was released in 1971, and was absolutely hated by Roald Dahl because of some scenes that differed from his book (he also hated that Gene Wilder was cast). But the movie has gained a much more positive reputation since then, and is personally one of my faves.
Clue. It was a bomb at the box office due to people’s confusion about when to watch the 3 different endings. It’s quite popular now as a cult movie though. Such a clever film.