Now that I've had a chance to take a look at these on my big computer, here is what I think...
WhiteBalance : Auto
ExposureProgram : Landscape
ISO : 1600
MeteringMode : Multi-segment
Flash : Off, Did not fire
You selected Landscape Mode, as I mentioned before. That means the flash will not fire, even if it thinks it should.
ISO was either set to 1600 or the camera selected it (I suppose that is what happened).
The flash did not fire.
Exposure was set to multi-segment.
White Balance was set to auto.
The odd exposures, I think, are due to the day-glo safety gear, which is fooling your camera's built-in exposure and white balance. Do you have any wonky photos in which such gear is not present?
Reflective stuff looks different to the human eye than it might to a camera's sensors. It reflects light in the visible and invisible spectrum, and the results are not something that the typical digital camera is set up to deal with.
http://www.canonrumors.com/forum/index.php?topic=4123.0
In the link above, the end-user had problems with their flash and reflective vests, but you don't need flash to confuse your exposure program. The reflective material sent more light back to your sensor than normal clothing does - which fooled the exposure program. It also had wonky colors - not usually seen - so it fooled the auto white balance.
That's my opinion. If you shot RAW, you might be able to tease something back out of these photos. I could not do anything with the JPG files, unfortunately.