Accidentally drop pieces of plastic in stew.

On the other hand, if there are many bits and they are hard to remove, this may be a fault in the product or packaging. If you have many pieces and still have the wrapping, consider returning the stew to the store. If no packaging and/or you don't want to ask for a refund, at the least, notify your store manager to look out for this problem....is it a one-off or occurring many times?

Not sure what Aldi uses as their meat trays, but if it is the typical styrofoam, the pieces won't hurt you and luckily they are soft enough you won't break a tooth. You could try slowly ladling the stew into a different container and pick out the plastic pieces as you go. I would also warn those you are serving there may be foreign objects in the dish. Not so different from finding cherry pits in a pie or cartilage in chicken soup.