The Clone Wars - S4E16 - "Friends and Enemies"

3:25 - Cad Bane looks at a hat like Indiana Jones':

[source]

7:44 - Some of the panels in the background have the same hexagon pattern that's also seen in the homestead garage in Attack of the Clones and A New Hope:

9:02 - Obi-Wan (as Hardeen) reaches up to his bound feet to use the Force to release them.  There's a similar shot in The Empire Strikes Back where Luke reaches up in a vain attempt to free his own bound feet [9:01]:

12:49 - Cad Bane (about Hardeen's suggestion to split Eval's reward fifty-fifty):  "Over my dead corpse."

Hardeen:  "Don't tempt me."

There's a similar exchange in A New Hope.  After Greedo tells Han Solo that Jabba may take his (Han's) ship, Han says, "Over my dead body" to which Greedo replies, "That's the idea" [50:42].

16:31 - Moralo Eval:  "Who sells a ship with only enough fuel to get to this lousy rock?"  In A New Hope, Luke also disdainfully calls a planet a rock; after C-3PO asks if there's anything he can do to help, he replies, "Not unless you can alter time, speed up the harvest, or teleport me off this rock" [19:58].

19:47 - Anakin:  "You're going to pay for what you did."

Hardeen:  "You shouldn't have gotten involved."

There are two similarities here.  In Attack of the Clones, Anakin says almost the same thing:  "You're gonna pay for all the Jedi that you killed today, Dooku" [2:04:51], and in A New Hope, Obi-Wan uses the same expression when he tells Luke, "He [Luke's uncle] didn't hold with your father's ideals, thought he should have stayed here and not gotten involved" [32:42].

---

Moralo Eval's armor is similar to that of General Veers, Dengar, and the snowtroopers:

[source]

The helmet that Hardeen wears is based on a piece of Ralph McQuarrie concept art for Boba Fett:

[source]

It's even mentioned specifically in this video:

The Clone Wars - S4E15 - "Deception"

3:13 - This shot of Ahsoka and Plo Koon at Obi-Wan's fake funeral is somewhat similar to a shot of Anakin and Obi-Wan at Qui-Gon's funeral in The Phantom Menace [2:07:35]:

7:27 - Rako Hardeen (as he sees Obi-Wan disguised as him):  "What the?"  In Attack of the Clones, an alien on Coruscant makes this same exclamation as he sees Obi-Wan flying through traffic while hanging from a droid [15:08]; Han Solo says it in A New Hope after emerging from hyperspace into a meteor shower [1:03:15], and in Return of the Jedi, a scout trooper says this after being hit by Wicket [1:05:38].

---

According to the trivia in the episode guide on the Star Wars website (my source for both of these images), Hardeen's helmet is based on a rebel trooper concept from Return of the Jedi.

The Clone Wars - S4E14 - "A Friend in Need"

19:53 - Ahsoka (to R2-D2):  "That's two I owe ya."  Han Solo has a similar line in The Empire Strikes Back (speaking to Luke):  "That's two you owe me, junior" [17:00].

The Clone Wars - S4E13 - "Escape from Kadavo"

13:35 - Zygerrian slaver:  "Keeper, a fleet of warships has dropped out of hyperspace in sector six."  One of the rebels says something similar in The Empire Strikes Back:  "General, there's a fleet of Star Destroyers coming out of hyperspace in sector four" [22:31].

13:46 - Plo Koon:  "Wolf leader to Wolf pack, accelerate to attack speed."  Red Leader also says, "Accelerate to attack speed" in A New Hope [1:45:56], and Lando says it in Return of the Jedi [1:35:19].

14:22 - Ahsoka:  "We'll need a bigger ship."  In Jaws, Chief Brody says something similar to Quint:  "You're gonna need a bigger boat" [1:21:24].

15:20:  Warthog (after Plo Koon shoots down two Zygerrians):  "Yeah!  That got 'em!"  Wedge has a similar exclamation in The Empire Strikes Back after one of the AT-ATs is blown up:  "Wooah!  That got him!" [29:24].

15:25 - Plo Koon:  "Watch out for those towers."  There's also some talk about towers in the attack on the Death Star in A New Hope. At 1:53:48, Wedge says, "My scope shows the tower, but I can't see the exhaust port. Are you sure the computer can hit it?" and then, "What about that tower?" to which Luke replies, "You worry about those fighters; I'll worry about the tower."

16:49 - Anakin:  "We are running out of time."  Qui-Gon also says this in The Phantom Menace:  "Either way, we're running out of time" [40:07].

17:55 - Anakin (after destroying the towers with gun emplacements):  "You're all clear, Master Plo."  Han Solo uses this same expression near the end of A New Hope:  "You're all clear, kid.  Now let's blow this thing and go home." [1:56:54]