Boss's "wise words to live by" plaques in his office read, "Do unto others before they do it to you" and "One bad turn deserves another."
The merc who phones Boss to let him know about the armoured truck's leaving on schedule is sitting on a bench with a painted advertisement for "Heist Construction"; this is an obvious play on words in that Boss and his hired goons are all conspiring to "construct" a "heist": they're arranging to rob the armoured truck and frame the Duke boys for it.