Yes there are some products you want to assume are fine and are surprised are not. So here's a list of some of the items I was surprised to find soy, dairy, egg or oats in. Some seem SOO obvious now..
Vegetable shortening and oil: It's all made from soybean oil. I've yet to find a solid shortening I can use that does NOT contain soy in one form or the other. Coconut oil, Canola oil and Olive oil are the only alternatives I've found. Unless you go to Goat butter..
Chicken bouillon and broth: They all seem to contain some form of soy as a preservative.
Cream of ... soups: Cream of Mushroom, chicken, broccoli any canned cream of soup contains dairy.
Meijer Organics Rice Milk: contains soy, try Rice Dream or Westsoy instead.
Country Time Lemonade mix: Pink and regular both contain soy.
Most Cake mixes, pancake mixes and cookie mixes: all seem to contain eggs and/or dairy in the mix. See my post of items you CAN use for alternatives.
Premixed spices. I have a few that are my favorites, but have now found that, they contain soy as a preservative. So watch your mixes, or just make your own.
Sherbert ice cream: I always thought it was an alternative, but no, actually it's not. it does contain dairy. Schwans carries a strawberry Sorbet that is dairy free and Popsicles are a great alternative too.