Cassiel is the Latin name of an archangel, notably the angel of solitude and tears, in post-biblical Judeo-Christian religion who is known for simply watching the events of the cosmos unfold with little interference.
The authorization to see the security control room is signed under the company name "Road Movie", which is Wim Wenders' production company.
Mikhail Gorbachev: only appears because his secretary was familiar with the movies of Wim Wenders and was a great admirer. She talked Gorbachev into giving up a couple of hours to do the cameo as he was on a trip to Germany anyway.
Yella Rottländer: appears in a cameo as the guardian angel of Phillip Winter, played by Rüdiger Vogler, recomposing the couple of leading actors in Wim Wenders's Alice in the Cities (1974) after 20 years.