Comment Passing Parameters with Side Effects (Score 3, Interesting) 285
I had a bug once where red and blue values were swapping places across thousands of pixels that took quite a while to hunt down once. It turns out there was a function doSomething called with parameters (pixel[i++],pixel[i++],pixel[i++]) while doing transformations. The compiled code pushed the third parameter onto the stack first, so it was using the red value from the array in the blue spot and vise-versa across the entire image.