Product placement isn't bad so long as it's obvious that it's product placement. When Subway offered them the cash, I'm sure the writers were given free reign on what to do with it.
You have to admit, making a KFC-brand space simulator ("We are 40 light years outside of the Buttermilk Nebula, although it's possible that … yeah, this is a sticker.") or an episode turning Subway into a literal human being are pretty ingenious ways to do product placement.
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