When Allison (Sarah Wayne Callies) tries to get Donk (Kyle Davis) and Reevis (Jon Reep) to leave town, they reply that the town is deserted, like in a "zombie apocalypse". Sarah Wayne Callies was a regular on The Walking Dead (2010), which deals about a zombie apocalypse.
Extras on set often broke out into song in between takes to raise the spirits of those who were wet/tired. A favorite amongst the extras was "Come Sail Away" by Styx.
When Gary is performing CPR on Donnie, he does it incorrectly. He does 23 chest compressions, and then 3 rescue breaths. Current Red Cross guidelines call for 30 chest compressions and only 2 rescue breaths. The hand placement is also wrong; Gary had his hands on Donnie's upper chest but CPR is performed about 2 finger widths above the lower tip of the sternum(breastbone). While this could be considered stress due to the moment, his late ex-wife was a nurse, and Donnie himself said that they learned CPR from her.