The English voice acting was provided by voice actors from 4Kids Entertainment, the company who provided the English dub of Pokemon and Yu-Gi-Oh. Jimmy and Pink Monkey are voiced by Veronica Taylor, who provided the voice of Ash, Ash's mom, and May from Pokemon. Natalie is voiced by Rachel Lillis, who provided the voice of Misty, Jesse, and Jigglypuff in Pokemon. The professor and Spike are voiced by Dan Green, who voiced both young Yugi and adult Yugi in Yu-Gi-Oh. Specter, Blue Monkey, and Red Monkey are voiced by Greg Abbey, who provided the voice of Tristan in Yu-Gi-Oh.

A number of monkeys found throughout the game have names that parody celebrities and other famous characters. These include:
• Tomkey Kruise - Tom Cruise
• Balboa - Rocky Balboa
• Baboondini - Houdini
• Count Monkula - Count Dracula
• The Invisible Monkey - The Invisible Man
• Hyde - Mr. Hyde (Dr. Jekyll and Mr. Hyde)
• Clint Apewood - Clint Eastwood
• Pelvis - Elvis

Two of the enemies in the game, Space Can and Submarine Lookalike, are taken from Space Fishermen, a game only released in Japan. There is only one of each of these enemies in Ape Escape 2, and their Enemy Cards say that they "came to the wrong game."