Captain Holt tells Jake that Kevin's parents are homophobes who haven't spoken to him since they met as they think Holt made Kevin gay.
In S2E04 The Halloween heist is centered around Captain Holt's watch which he tells Jake was given to him by Kevin's father shortly before he died.
The subplot about Jake and Victor investigating one of Victor's old cases ends with them arresting a woman who robbed a bank twenty years prior. The statute of limitations on bank robbery in New York is 5 years.
Captain Holt wears his Commendation breast bar above his World Trade Center Breast Bar. When the WTC bar is worn, it is worn above all other medals, but below the American Flag bar.
Although totally in character for Jake to brutally mangle the name of the German watch manufacturer, the correct pronunciation of "Glashütte" is of course not "glashute". The "s" and the "h" are separate consonants, not an "sh" sound. That would be spelled "sch" in German. And the last vowel is the umlaut "ü" (which sounds like the Scottish pronunciation of "oo"), not the normal "u".
Neither Amy, being the self-admitted control freak, nor Boyle, being the self-admitted good cook, acknowledge the fact that you cannot prepare turkey for (Thanksgiving) dinner party while the guests are waiting.
It makes no sense that not a single one of Amy's party guests should know that it takes hours and hours to prepare and fully cook a turkey. They have had hundreds of Thanksgiving dinners between them. As soon as it came out that Boyle had ordered a live turkey which had not even be delivered yet, somebody would have pointed that out and started to complain.