This episode marks the first appearance of Siegfried (Bernie Kopell), although in season 2 his name is spelled 'Seigfried'. He would appear a total of 14 times in the last four seasons.
The title is from the biblical reference, "an eye for an eye."
Sigfried's line, "Leave the spying to us" is a reference to the advertising slogan of the time for Greyhound Bus Lines: "Take the bus and leave the driving to us."
(At around 10 minutes, 30 seconds) As Max and Siegfried are removing the cache of weapons each is carrying, Max pulls out his XKE-500 pistol. Impressed, Siegfried asks if it is CONTROL-issue. Max states that it isn't, then adds, "I got it from a mail-order house in Chicago." This may be a reference to the John Kennedy assassination, which was still a popular topic at the time. The Warren Commission Report stated that accused assassin Lee Harvey Oswald bought the alleged murder weapon, a Mannlicher-Carcano rifle, by mail from Klein's Sporting Goods in Chicago.