The officer of the day at Escola Prática de Cavalaria, Liutenent Lobão, doesn't wear the red band at his left arm that all all officers of the day must wear to identify them as such.
There are many factual and historical mistakes in the movie: Salgueiro Maia wasn't present when "Grândola, Vila Morena" is heard in the movie. This song (that's the revolution anthem) was broadcast in radio at 00.20 AM 25 April and only by 3 PM Maia addresses the soldiers explaining them the main goals of the revolution; he wasn't neither present when political prisoners were released in 26 April 1974.