The Centauri Emperor had no personal name in the script. But Executive Producer J. Michael Straczynski was so impressed with actor Turhan Bey's performance that he later named the character, Emperor Turhan, in the man's honor.
The cast so enjoyed Turhan Bey's performance that many were upset that his character was killed off so quickly. So, Executive Producer J. Michael Straczynski had Bey return three years later to play Sech Turval, a Minbari teacher.
According to Babylon 5 canon, the Ranger (Fredric Lehne), actually had three message crystals: one for Garibaldi, one for Delenn, and a third which deposited a message into Catherine Sakai's account. The message to Sakai told her to come to see Sinclair on Minbar.
G'Kar shattering his stone desk into pieces when he picks it up in a fit of rage and throws it on the ground was completely unplanned, but it emphasized and underscored what had just happened (he had just learned of Quadrant 14's destruction, supposedly at the hands of the Centauri), due to the importance of this episode in Babylon 5's overall story.
A part of the message to Garibaldi that was not seen was Sinclair asking Garibaldi not to tell Sheridan what he was about to hear. Garibaldi later confirmed this when he told Sheridan that he gave his word not to reveal his informational source.