Star Wars Rogue One: 37 Easter Eggs & References You Must See
23. BT-15s Are "Obsolete"
In A New Hope, two Stormtroopers are overhead talking about the new BT-16 perimeter droids, with one asking, "You seen that new BT-16?", before the other replies, "Yeah, some of the other guys were telling me about it. They say it's…it's quite a thing to see."
Hilariously, this pays off with a referential conversation between two other Stormtroopers in Rogue One, with one mentioning that the BT-15 is obsolete, implying that this led to the introduction of the BT-16s.
As if that's not enough, The Force Awakens also includes a nod, with a Stormtrooper mentioning that the BT-17s aren't as good as promised when Rey is sneaking around the Starkiller Base.