OCID is short for Organized Crime Investigation Division
Tom Cavanagh (Mickey) and David Ramsey (Mayor Carter Poole) would both go onto star in the Arrowverse. Tom on The Flash (2014) and David in Arrow (2012), appearing on several crossover episodes.
As they set up the sting operation on Mickey, Lieutenant Sutton assures Danny (Donnie Wahlberg) that if anything goes wrong, his men would come busting in "like Normandy". To which Danny replies, "Normandy was a bloodbath!" Donnie Wahlberg played a prominent role in the miniseries Band of Brothers (2001), the first three episodes of which depicted the preparation and participation of the 101st Airborne Division in the invasion of Normandy in June, 1944.
Guest star Rebecca Buddig had her debut as a female workout partner in the 1993 video Form... Focus... Fitness, the Marky Mark Workout. "Marky Mark" Wahlberg is the younger brother of Blue Bloods series star Donnie Wahlberg.
The language "Ob" Danny and Mickey use is similar to a language called "Ubbi Dubbi" featured on a kid's show called Zoom, which aired on WGBH Boston from 1972-1978. Ob inserts an ob before every vowel; Ubbi Dubbi inserts a ub before every vowel.