Human Hair and / or Duck Feathers in Bread
Interestingly enough human hair and / or duck freathers is the substance called L-cysteine or cystine, and is used as a dough conditioner to produce a specific consistency. While artificial cysteine is available, it is cost prohibitive and mostly used to create kosher and halal products.
Coal Tar in Red-Coloured Candy
Coal tar is listed as number 199 on the United Nations list of "dangerous goods", but that doesnt stop people from using it in food. The colouring Allura Red AC is derived from coal tar and is comonly found in red_coloured candies, sodas and other sweets.
Sand in chili
Sand is hidden in Wendy"s Chili as a name you might remember from High School chemistery class: silicon dioxde. Apparently they use sand as an "anti-caking agent".
Crushed Bugs as Red Food Colouring
After killing thousands at a time, the dried insects are boiled to produce a liquid solution that can be turned to a dye using a variety of treatments. Some people worry that the colouring - often called carmine or carminic acid - could be listed as a "natural colour" disguising the fact that there are bugs in the product.