The following is from the program book published in 1951.
The more spectacular scenes of the film including the triumphal procession in front of Nero’s palace, the burning of Rome, the banquet scene and the sequences which take place in the huge circus of Nero had to be mapped out on paper in advance with the same attention to minute detail that a modern army might employ prior to a full-scale land and sea invasion.
In the first place an entirely separate organization had to be created to handle the mechanics of these big scenes. Extra help had to be procured in the casting, wardrobe, make-up and accounting departments. It was necessary to construct on the outdoor lot a cafeteria capable of feeding 2,000 persons in 20-minute sittings. Six large first aid stations, fully staffed with doctors and nurses, had to be established at strategic points in anticipation of the emergency medical cases that would surely arise.
On most of these big scenes four Technicolor cameras were used simultaneously to cover the sequence from every angle. For the triumphal procession alone four camera towers (one, 150 feet high) were erected. Sixteen assistant directors, most of them Italian were hired to work with the big crowds. They were used to transmit orders from Director LeRoy to the thousands of extras, much in the manner of army sergeants relaying commands of superiors.
Days before each scene was scheduled to go before the cameras, members of the casting began notifying extras, all of whom had been catalogued previously. The problems of this task become obvious when it is considered that 85 percent of those who applied had no telephone and many had no specific address, merely indicating they could be reached through such and such a friend.
As the mob extras (called comparse) were engaged, they were placed in charged of an experienced extra (or genereci) who there after would be responsible for getting those in his group to work on time. It would be his duty also to see that his unit (usually 30 in number) moved in and out of wardrobe and make-up promptly, and that group remained close together on the set. At the end he would be paid and left to distribute the money to the individuals under his command.
To handle mobs of people without confusion the first unit moved into wardrobe at five in the morning; often the last group would not be cleared until ten at night. So that the various units would know where to assemble on the sets, different colored flags were set up. Then the various groups would gather at the flag which had been designated as their symbol.
Typical of the complex call sheets which went to the casting department prior to the big scenes was the following, issued in connection with the triumphal procession sequence.The department was asked to procure: 10 Roman generals; five Egyptian dignitaries; five Syrian dignitaries; five African
dignitaries; 40 Praetorian guards; 30 standard bearers; seven cavalry officers; 295 cavalry; 79 members of the band; six infantry officers; 12 infantry non-coms; 708 infantry soldiers; 10 dancing priests; 10 trumpeters; 36 women choir singers; 10 vestal virgins; 24 flower girls; 115 high class men; 510middle class men; 1,750 lower class men; and a corresponding number of women, their various classes to be indicated by dress.
It was also necessary for five rams, three cows and three calves to be garlanded in flowers since they were supposed to be sacrificed to Nero on an altar of fire. In addition there were 350 horses, many of them pulling chariots. The other spectacle scenes required personnel just asvaried and as colorful. A few more photos: