Sabrina: The Animated Series (1999)

S1E39 When in Rome

Gem and Sabrina, paired up by their history teacher for a project on Rome, find themselves in a predicament when Gem's snobby behavior leads her to conceal their Rome book in a spooky jar. This unexpected act transports them to ancient Rome, where they are forced to compete against each other in challenges set by Julius Caesar. Ultimately, they both agree on the need to return home. Once back, they complete their report, but Gem undergoes a brainwashing experience. In the end, Sabrina realizes that despite their differences, they make an excellent team.