When the studio suits meddle in the production

[Tosk]

That brings to mind Dark City, where the director was forced to add the opening narration

One of the worst of all time.

"Here's me, Kiefer Sutherland, explaining the entire mystery of what will slowly unfold for the first half of the film..."

 

[Aragorn]

I'm watching Snowpiercer and I looked at the Wikipedia entry for the making of the movie.
Harvey Weinstein wanted to cut over twenty minutes from the movie and add an opening/closing narration and a happy ending.
A disastrous test screening of his preferred cut meant that director Boon Joon-ho got the final say; however, Weinstein got his revenge by releasing the movie in only 356 theaters.

Weinstein destroyed a lot of movies by cutting them down to two hours so they could have more showings per day.

For some reason Stallone did it to himself once, completely butchering Cobra to get it down to 90 minutes so it could have more showings per day because Top Gun was owning the box office.