All throughout Timeline, I couldn't help thinking of Bill & Ted's Excellent Adventure. Paul Walker, who plays Chris Johnston, is clearly his generation's Keanu Reeves. In Timeline, he time-travels back to the Middle Ages, in the process learning about history and falling in love. He has a most excellent adventure. And with his wooden acting, surfer-dude looks and tendency to say "bro" and "dude," Walker's got all his Keanu-isms down.
Chris goes back to 1357 to track down his archaeologist pop (Billy Connelly), who's gotten himself trapped in the past courtesy of some poorly-explained techno-babble from the company that funds his digs. Joining Chris are archaeologists Marek (Gerard Butler) and Kate (Frances O'Connor), plus a few more throw-away characters. They're plopped right in the middle of a siege during the Hundred Years' War, so they've got to engage in swordplay as they look for the lost professor. And while, unlike Ted, Chris doesn't bring back a historical babe to wed, Marek does get to hook up with a French noblewoman.
The movie is an adaptation of Michael Crichton's novel, and like most Crichton adaptations, it eschews the author's focus on meticulous research in favor of action and characterization, with fighting and love stories taking precedence over quantum physics and 14th century life. Director Richard Donner has made action classics like Lethal Weapon and Superman, and he stages some decent battles, but nothing's got any great sense of urgency. The love stories are worse, coming as they do amidst the supposedly frantic effort to save the professor, stay alive and get back to the present.
The best Crichton adaptations have kept his sense of awe of science and nature even if they don't retain all the technical details. Timeline treats the past like an amusement park, offering mid-level thrills and nothing more.