The road on which all the abductions occur is road 406. This is probably part of the episode-number running gag of the show, incorporating the episode numbers in the actual episodes, being episode 6 in season 4.
Opens with the quote, "There is no mercy in you. You cut off the heads of men and women and these you wear as a garland around your neck." This is attributed to the Hindu poet Ramprasad writing about Kali.
The SS Panzer Division using the Wolfsangel Monroe refers to is the 2nd SS PZ Div 'Das Reich'. The symbol is also used by the 4th SS Panzer Grenadier (mechanized infantry) Div 'Polizei', and the 34th SS Volunteer Grenadier (Infantry) Div. 'Landstorm Nederland', as well as numerous German coats-of-arms.
Griffin says "What the hell is this?" when looking at some evidence to which Wu replies "The stuff nightmares are made of." This is a play on The Maltese Falcon when Humphrey Bogart is asked what the falcon is, to which he replies "The stuff that dreams are made of."
The episode title is likely a nod to British Columbia's (Canada) Highway 16, dubbed Highway of Tears since at least 1998, when a vigil was held for 6 missing Indigenous women at that time. The total estimated number of missing and/or murdered women thought to have been abducted from the area since then ranges (depending on the source) anywhere from 16 to as high as 40.