Os gladiadores foram forçados a lutar em encenações históricas, como fizeram em "Gladiator"?

Sim. Acredita-se até que o Coliseu em Roma estava cheio de água às vezes para reencenar as batalhas navais. Do Wiki :

The Colosseum could hold, it is estimated, between 50,000 and 80,000 spectators, having an average audience of some 65,000; it was used for gladiatorial contests and public spectacles such as mock sea battles, animal hunts, executions, re-enactments of famous battles, and dramas based on Classical mythology. The building ceased to be used for entertainment in the early medieval era. It was later reused for such purposes as housing, workshops, quarters for a religious order, a fortress, a quarry, and a Christian shrine.

Embora os eventos do filme não tenham sido inteiramente factuais, o conceito e a apresentação foram precisos quanto ao que aconteceu lá.

Sim, aconteceu.

De Origens Antigas ,

The activities which held Commodus’ attention and with which he spent his time were in the nature of “gladiatorial combat.” He would take to the arena and engage in combat which the Romans viewed as being scandalous and disgraceful. He was very vain, and strongly believed himself to be the reincarnation of Hercules – so much so that he ordered statues of himself be dressed like Hercules, and he ordered that people call him Hercules, son of Zeus.

Este artigo sugere que os romanos fizeram a reencenação de maneira mais espetacular.

Sometimes, indeed, remarkable liberties were taken with the biographies of the heroes which were “revised” to make them more spectacular and to provide a bloody end. In one of these dramas, of which unfortunately, we do not possess the complete scenario, Daedalus does not reach his destination; as he flies over the arena, his wings fail him. A bear awaits him on the ground.

Mais exemplos podem ser encontrados neste artigo. Por exemplo,

On the summit was chained a man, half-naked, playing the “poetic” role of the celebrated brigand Selurus, the terror of Sicily, perhaps also of Prometheus chained to his rock. But he was a man of flesh and blood, and one could see from the rise and fall of his chest that he was afraid to die. Before the crowd had finished feasting its eyes on the spectacle, the mountain had fallen to pieces and the “bandit” had been precipitated still alive among the cages of wild beasts, which had been fastened in such a way as to open at the slightest touch.

Essas outras duas respostas são ótimas, mas eu gostaria apenas de adicionar algumas informações mais interessantes. A maioria dessas informações vem de uma grande fonte chamada "Jogos Assassinos" no website www. Href="http://www.historytoday.com/keith-hopkins/murderous-games-gladiatorial-contests-ancient-rome"> .historytoday.com .

Demorou muitos anos para que reconstituições históricas se tornassem comuns.

The Colosseum was dedicated in AD 80 with 100 straight days of "games". In one single day over 3,000 men fought; along with another 9,000 animals being killed.

...

The Emperor Trajan, to celebrate his conquest of Dacia (roughly modern Roumania), gave games in AD 108-9 lasting 123 days in which 9,138 gladiators fought and eleven thousand animals were slain. The Emperor Claudius in AD 52 presided in full military regalia over a battle on a lake near Rome between two naval squadrons, manned for the occasion by 19,000 forced combatants. The palace guard, stationed behind stout barricades, which also prevented the combatants from escaping, bombarded the ships with missiles from catapaults. After a faltering start, because the men refused to fight, the battle according to Tacitus 'was fought with the spirit of free men, although between criminals. After much bloodshed, those who survived were spared extermination'.

[He] tells of a visit he once paid to the arena. He arrived in the middle of the day, during the mass execution of criminals, staged as an entertainment in the interval between the wild-beast show in the morning and the gladiatorial show of the afternoon:

All the previous fighting had been merciful by comparison. Now finesse is set aside, and we have pure unadulterated murder. The combatants have no protective covering; their entire bodies are exposed to the blows. No blow falls in vain. This is what lots of people prefer to the regular contests, and even to those which are put on by popular request. And it is obvious why. There is no helmet, no shield to repel the blade. Why have armour? Why bother with skill? All that just delays death.

In the morning, men are thrown to lions and bears. At mid-day they are thrown to the spectators themselves. No sooner has a man killed, than they shout for him to kill another, or to be killed. The final victor is kept for some other slaughter. In the end, every fighter dies. And all this goes on while the arena is half empty.

Aqui está outro fato interessante sobre o Coliseu. Pode acomodar cerca de 50.000 pessoas. E teve o primeiro teto retrátil do mundo. Algo como os estádios modernos, o Coliseu usou um sistema muito complexo de toldos, que eles chamavam de "Velarium". Esse sistema de cortinas protegia a multidão dos elementos como o sol e a chuva. Mas o principal uso do velário foi criar uma corrente de ventilação e circular a arena com uma brisa fresca.