I used to work at a snack foods factory and was checking on some equipment (that actually wasn’t the equipment I was supposed to be checking–I got my lines mixed up). It was adjacent to a conveyor that had crumbs from a different product on it, which was supposed to be turned off since we weren’t producing it that day. Said crumbs were spilling into another conveyor below it* that was in use delivering a currently-running product. These two products had non-overlapping allergenic ingredients (soy-containing crumbs were spilling into a soy-free product).
I alerted management to get the batch scrapped since it was contaminated.
If I hadn’t mistakenly checked the wrong equipment, it’s unlikely anyone would have noticed and A LOT of contaminated product could have been shipped. All products from that factory are labeled “MAY contain X, Y, Z” so in theory nobody with a severe allergy to X/Y/Z should be eating anything from there anyway, but consumers make mistakes and even a non-severe dietary allergic reaction is an unfun time I wouldn’t wish on anyone.
*It didn’t just always spill into the conveyor below it, it was supposed to have a catch pan but someone had forgotten to replace the catch pan after cleaning it.
Yeah it was… not a very clean place