The 7th Voyage of Sinbad

Legendary adventurer Sinbad the Sailor (Kerwin Mathews) and his crew land their ship on the island of Colossa, where they encounter Sokurah the magician (Torin Thatcher) fleeing from a giant cyclops. Though escaping with their lives, Sokurah loses a magic lamp to the creature. Sinbad refuses his desperate pleas to be returned to the island because he is carrying Princess Parisa (Kathryn Grant) aboard. Sinbad has fallen in love with her, and their coming marriage is meant to secure peace between her father's realm and Sinbad's homeland of Persia.




Sinbad and his men confront the Roc.
After reaching Bagdad, the wedding is prepared, and Parisa's father (Harold Kasket) arrives as the guest of honor. Sokurah performs his magic at the pre-wedding festivities, but despite his prowess the Caliph of Bagdad (Alec Mango) refuses to grant the magician his return to Colossa. Later that night, Sokurah secretly reduces the princess to diminutive size, enraging her father who then declares war on Bagdad. Sinbad and the Caliph give in to Sokurah, who explains that the eggshell of a Roc needed for the potion to release Parisah from her spell can be found only on Colossa. Sokurah provides Sinbad and his crew with the construction plans for a giant crossbow, if needed, to be used against the island's giant creatures.
Sinbad recruits additional sailors for the voyage from among the convicts in the Caliph's prisons. Before they reach Colossa, the cutthroats mutiny and capture Sokurah, Sinbad, and his men. During a violent storm, the sounds of keening demons from an island south of Colossa drives the crew nearly mad, endangering the ship. After the mutineers' leader falls to his death from the Crow's nest, one of them releases Sinbad so he can save the ship.
On Colossa, Sinbad, Sokurah, and some of the crew enter the Valley of the Cyclops, where they find the creature's treasure cave. Sinbad and his men are captured after Sokurah regains the magic lamp, but he is also trapped by the Cyclops. With Parisah's aid, Sinbad escapes, blinds the one-eyed creature, and lures it off the edge of a cliff to its death. Sinbad retains custody of the lamp until Parisah is turned back to normal.
Sokurah leads Sinbad and his starving men to the nesting place of the giant Rocs, finding an intact egg close to hatching. Sinbad's men crack it open and kill the Roc nestling inside, roasting it. While the men are eating, Parisah enters the magic lamp and befriends the childlike Genie of the lamp, Barani (Richard Eyer), who tells her how to summon him in exchange for her promise for his freedom. The parent Roc returns and slays several of the men. Sinbad manages to retrieve both an eggshell fragment and the lamp, but he is grabbed up by the Roc, who later drops him unconscious in its nest. The magician kills Sinbad's aide Harufa (Alfred Brown) and abducts the princess, taking her to his underground fortress.
Sinbad awakes and rubs the magic lamp, summoning Barani, who takes Sinbad to Sokurah's fortress. Barani helps him evade the chained dragon that stands guard. Sinbad reaches Sokurah, who restores the princess to normal. When Sinbad refuses to hand over the lamp, the magician animates a skeleton warrior, which Sinbad battles and destroys. He and Parisah make their way out of the cave, stopping to honor their promise to destroy the lamp, setting Barini free.
Leaving the cave, they encounter another cyclops. Sinbad releases the dragon, who fights the cyclops to the death. Sinbad and Parisa make good their escape, and Sokurah orders the dragon to follow and kill them. Sinbad's men, having assembled and armed the giant crossbow, manage to kill the dragon with a giant arrow. As it dies, Sokurah is crushed beneath the collapsing creature. Sinbad, Parisa, and the remaining crew depart for Bagdad to stop the war. They are joined by Barani, now human and Sinbad's new cabin boy, who, before his transformation, magically placed the treasure of the Cyclops in Sinbad's cabin as a wedding gift.

Question: How did Sinbad's men kill the dragon?
Answer: Giant arrow