During production, only one camera was being used at the time and suffered major technical malfunctions, which resulted in the entire first half of the movie to being completely re-shot.
The broken mug shards were left in place after their initial smash destruction. In one scene where a shard is seen sticking into the wall, that was from the original velocity of the force impact onto the floor and was added as a new shot on the spot to help transition the scene.
Originally shot in 2007, the 2017 release had two minutes of footage removed - a post-directorial choice made to enable the story to move faster and more efficient.
No animals harmed: The dead shark in the glass jar is an actual dead shark preserved in formaldehyde which had been purchased at a water park exhibit some years prior and the bird, which drops dead from the overhead power line, is not the same as what's seen alive. The bird which falls, however, was found dead nearby in a parking lot and later added in as an improvised story-filler element to lament upon the character's discovery.
The cocaine scene was completely improvised and unscripted. The original script just stated a generic flashback argument had ensued between the two main characters, but did not outline any specific incident in detail.