3) Pink meat
Sometimes the purple in bones can discolor the meat touching them and they remain pink even though the meat is safely cooked. Sometimes the pink color can come from nitric oxide (NO) or carbon monoxide (CO) produced by the cooker. NO and CO can be byproducts of combustion in gas ovens and grills, as well as charcoal and wood grills.
This pink meat can be soft and spread evenly throughout the meat, or it can take the form of a distinctive band called a smoke ring which is right below the surface. USDA says "All the meat—including any that remains pink—is safe to eat as soon as all parts reach at least 165°F as measured with a food thermometer. Often meat of younger birds [can be] pink because their thinner skins permit oven gases to reach the flesh. Older animals have a fat layer under their skin, giving the flesh added protection from the gases. Older poultry may be pink in spots where fat is absent from the skin. Also, nitrates and nitrites, which are often used as preservatives or may occur naturally in the feed or water supply used, can cause a pink color."
And of course, meat can become pink as a result of chemical reactions that happen during smoking. The pink band called a smoke ring is right under the skin, and can sometimes extend as much as 1/2" into the meat. Click here to read more about smoke rings and what causes them.
