When Gina and Jake are talking about ideas for Charles' gift at the beginning of the episode, the same female black police officer walks out of a room behind Jake twice.
When Rosa, Holt, and Amy are toasting on the beach, Rosa can be seen wearing some sort of socks or boots that go up to mid-calf. When they shed their coats and run towards the water, she is suddenly barefoot.
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.
When Jake Charles and Gina are in the store and first figure out that it is being robbed Jake can be heard saying shoot their being robbed, but if you look at his mouth he is actually saying anther s word instead.
When Jake hit Gunter across the face with the curtain rod, Gunter's reaction to the blow was very delayed.