I just discovered this thread was here and I'm glad, because I recently saw ghost rider for the first time and almost hurt myself laughing at it.
Probably one of my favorite worst movies is Bitter Lake, aka shitty furry game of thrones. Basically it's a fantasy story where everyone is in fursuits, and apparently there were huge amounts of money backing it. The furry part of it is actually the most benign element (the fursuits themselves are well-made stuff), the rest of the movie is baffling for how boring the plot is, how badly acted it is (none of the actors actually attempt to put any body language into their acting other than a few drama-class level gestures, and there's a laughable "chase scene" at the start where two of the actors barely shuffle along, and later a fight scene where two actors awkwardly smack some swords together), and the fact that despite renting out an entire lakeside cottage area to shoot the film at and doing extensive work to make it more medieval-looking (they have a behind-the-scenes special feature where you see them repainting things and so on), it's still obviously a modern-day holiday cottage and not the medieval fantasy setting they desperately want you to think it is.
Also, some fun facts: the person in the black wolf with horns fursuit is the director of the film, he literally made himself a self-insert. There were also two whole women involved with the entire production, the one who was in the fursuit of the single female character, and the person who voiced the single female character.
Also, there was a sequence in the making-of feature that you will no longer see, where the director pretended to be getting a blowjob from the head of his own fursuit. This is no longer in the special features, for reasons you can probably guess.
Other horrible movies I have had the "pleasure" of seeing are the baffling incoherant mess of a story that is Harmegeddon, which is a movie that had many good people working on it and still turned into the godawful mess it is, and Tristan and Isolde, a french animated film where the least of its offenses is having every single character look like they belong in a different film and having the perspective change radically during pans over the environment. And adding in Puck of Shakespeare lore to be the token wacky talking animal because why not.