In one scene when they're trying to catch the parakeet, it's resting on a branch just outside the diner. It was originally planned that they would try to sneak up on it to catch it. But it unexpectedly flew at Kevin and landed on his shoulder after he dropped to the ground. They had wranglers training the bird, but it was never supposed to do this. In the audio commentary, Kevin Downes said "I had no idea the bird was going to come after me......I'm going down to protect my eye cause I think the bird is coming at my eye". They decided that this was funnier than trying to sneak up on it, so they left it this way.
Trace Adkins (Bones) and Randy McDowell (Hank) became good friends, but when Bones head butts him, it wasn't as much acting as it was real. Randy had a mark on his forehead right afterwards.
Originally the character "Bones" was only going to be seen briefly, just outside the tattoo parlor. But they really liked him, and as the budget grew, they decided to use him a lot more.