One of the great things about film, you may not agree, is how color film can get a little squirrely towards the end of the roll or at the beginning of a roll. It's no secret that film is VERY light sensitive, but what is a mystery is how film reacts to a quick, unexpected exposure to light. Sometimes you get yellow or blue streaks; it's also common to get a vertical orange band at the end of a roll. I've never noticed this with B&W film, probably because I develop it myself and am very careful, but I sometimes end up with color film negatives that have a surprise at the beginning or end of the roll.
This roll was totally my fault, not the labs, because for some reason I hadn't advanced the film and I couldn't remember if I had a roll in the camera at all. We have ALL been there before, right? I opened the camera back up as fast as I could and there was a roll of film (Kodak Ektar 100) already in there. Doh! I knew my first frame or two woud be ruined, but I wasn't expecting anything as cool as this.
This reminds me of the time that someone once asked me on Tumblr, "If I opened the back of my camera "real fast" will you get light leaks?" My answer was, and still is, "Are you faster than the speed of light?" In my case the answer is not even close.