The acting

That's just lazy producing.

https://tvtropes.org/pmwiki/pmwiki.php/TroubledProduction/FilmOToZ

Fragasso brought over his all-Italian crew to the United States to begin filming at Morgan, Utah. However, only the costume designer spoke any English. This communication barrier led to much confusion between the English-speaking cast and the Italian-speaking crew. Compounding this problem was the fact that Fragasso refused any kind of assistance from any English speaking crew or cast. The cast would later state that they had no idea what was going on.

To compound the cast's confusion, none of them were aware they were getting lead roles, and they had no experience as actors. The casting call from nearby towns was specifically stated to be for extras alone, only for Fragasso to declare that the people who had showed up were going to be playing lead roles. One of the most ridiculous examples of this was George Hardy, a local dentist with no prior acting experience who showed up on the set one day for fun, only to be given one of the largest speaking roles. Similarly, Don Packard, who played the store owner, later stated that he was on a day trip after being released from treatment at a local mental hospital, and had—in his words—smoked an enormous amount of marijuana prior to showing up on set. His disturbed demeanor is evidently not acting.

Fragasso wrote the script himself, but only had a tentative grasp of the English language. This created a script that has been repeatedly described as "written in pidgin English". This was further compounded by the fact that Fragasso insisted that the script be read verbatim. He later claimed that he "knew how Americans spoke better than they did" and would repeatedly deny the cast members attempts to make what they said more grammatically correct and sensible. On top of that, they were only given parts of their script on a scene-by-scene basis, so rarely did they get any kind of context as to what was supposed to be happening.