Seen several times throughout the Citadel are mouse droids, the same little boxy droids seen as messengers aboard the Death Star and Star Destroyers in the original trilogy, and on Mustafar in Episode III.
Anakin's hopping on a STAP is an echo from way back in 2008, The Clone Wars animated story.
The entire sequence where Obi-Wan and Even Piell try to sneak around the landing platform when they emerge from the ventilation duct was originally shot on top of the citadel tower. It was later moved with minimal pickups to the landing area behind the tower, on the ground.
Obi-Wan's line to Osi Sobeck, "I must say, you're not at all what I pictured. Someone with such a soft voice," is particularly ironic given that actor James Arnold Taylor voices both characters.
The monitoring devices along the walls of the Citadel seen in these three episodes are designed after similar devices seen aboard the Death Star in Episode IV.
The non-existent Separatist outpost that OOM-10 mentions as part of his bluff is Point Tarron.
To differentiate Lola Sayu's hellish conditions from the lava planet Mustafar, its molten rivers are colored a bright yellow, to suggest sulfur. Given what sulfurous deposits smell like, it's understandable Tarkin and Anakin hold their noses.
