Ahsoka calls Cad Bane a 'Sleemo', which is Huttese for 'Slimeball'.
One of the Clone Troopers bangs his head against a pipe, in homage to the Stormtrooper in Star Wars: Episode IV - A New Hope (1977) who banged his head against a door. In the original version of the film, the bang was silent, but after many viewers spotted the mistake, a sound effect was added to it for the Special Edition, and it has become something of a running joke in the Star Wars franchise since.
After Rex tells his men to 'switch to night vision', the Aurebesh text in the margins of their view-screens translates to 'Regular Mode' (top left) and 'Infrared Mode' (bottom right).
The first time in the show that Ahsoka is seen without her usual outfit.
The 'Jedi fortune cookie' message that opens the show reads "Overconfidence is the most dangerous form of carelessness."