22 & 23. In the steps scene in the picture below, there are two things hidden. 22 is that one droid has a missing shadow. 23 is that on the back of one battle droid, his designation is clear the Dolby Digital logo.
24. When Obi-Wan pushes some battle droids away with the Force, they shriek a loud "D'oh!" Maybe it's because Homer Simpson programed them.