Dr. Horrible's Sing-Along Blog (2008)

Act II - S1-E2

Revealing mistake: During "Brand New Day", watch the background as Dr. Horrible appears as a giant and stomps down the city-street. As he takes his first step, a piece of concrete from building to his right falls off and hits the ground. However, if you look closely, it's obviously a quickly-made computer effect. As the piece of concrete hits the ground, it simply vanishes, and is replaced by a rather odd-looking animated "poof" of dust. The issue is the concrete piece was much bigger than the cloud of dust, so it's clear that the piece simply disappears right as the dust-poof appears.

Dr. Horrible: I don't have time for a grudge match with every poser in a parka.

Trivia: The film was written during the 2007-2008 Writer's Guild strike, which served as an inspiration for the production. Director/Co-Writer Joss Whedon, whom took part in the strike, wanted to make an independent project that he could create without having to deal with the red-tape of studios, unions, etc. Essentially to avoid the same sort-of issues that caused the strike in the first place.