The sign found around the dead ranger's neck on Babylon 5 is not the same one the killer put there.
Zack Allen continues to wear the uniform Delenn had created for the command staff, yet Captain Lochley is a by-the-book soldier, who should have ordered Zack to wear the original regulation uniform, but didn't.
When Sheridan first comes to G'Kar's quarters to ask him to write his swearing-in, Andreas Katsulas leans his head down so far the back of his prosthetic mask pops out of his costume.
Sheridan says that there are no planets where the telepaths could go, but that is not true. The Markab race died out in the second season, and Sheridan later destroyed the jump-gate there in a battle with the Shadows. The Markab homeworld would be isolated, and have empty cities awaiting new inhabitants, perfect for the telepaths.
Garibaldi references President Clark being "kicked out of office". Clark was not removed from office. He killed himself.