Ben is Griffin's best friend, known for his loyalty and more cautious nature, and he faces challenges due to his narcolepsy and the possibility of attending a boarding school.

Savannah is passionate about animals and plays a supporting role in the group's operations, known for her fierce advocacy for animal rights.

Mr. Nastase is the antagonist and owner of All Aboard Animals, whose actions oppose the children's efforts.

Klaus is the security guard at All Aboard Animals, who becomes protective of the children and reassesses his loyalties as the story progresses.

Darren is a classmate of Griffin's who considers himself superior to others, leading to trouble when he tries to manipulate events for his benefit.

Melissa is the technology expert of Griffin's group, characterized by her quiet nature and expertise with computers.

Pitch is the athletic member of the group, quick to act and valued for her outdoor knowledge and climbing skills.

Logan is an actor who uses his skills to create distractions for the group, adding comic relief with his humor and seeking recognition for his talents.