Captain Ryuya, the descendant of Tatsuya Asami, serves as the ultimate mastermind behind everything that occurred in the series. He helped Don Dolneiro to escape from captivity and releasing the other Londerz prisoners who would wreak havoc on the present, with one even trying to release a virus to poison an entire city. He would later drive Gien—who was a 5-year-old—-to insanity, which lead to his death. He was responsible for the crisis that took place in the finale (he had seen two futures—one in which 1/3 of the 21st century is destroyed and one in which the 31st century ceases to exist). Willing to kill billions of innocents to save his own hide, he is everything the Timerangers are not.
"Case File 11: Death Match City": Sadist Gougan is a prisoner released by Don Dolnero to kill the Timerangers. Imprisoned for horrific crimes committed with a "Dream Breaker," a device which forces people to murder each other in their sleep, Gougan wastes no time trying to indulge himself in horrific violence once more. Taking over a city, Gougan pits the citizens against each other, planning to ensure that they are all wiped out for his amusement, in addition to trying to kill the Timerangers' ally Honami. When the Timerangers arrive, Gougan tries to murder them as well, relishing the opportunity to murder en masse as he once did. Fueled by nothing but a love of destruction and death, Gougan cements himself, despite his one-episode appearance, as one of the worst criminals the Timerangers ever faced.
In the final, special episode tributing the past Sentai in Mirai Sentai Timeranger, Domon started praising how Choudenshi Bioman started the trend of 'two women in a team'. But had this Sentai played Two Girls to a Team straight, Domon himself will most likely be replaced, being a yellow ranger himself.
For bonus points, the fact that his Power Ranger counterpart, Katie Walker, is female.
Episode 10's Monster of the Week is called Mercenary Org. You'd be forgiven for thinking that said episode was one featuring an Early-Bird Cameo by the next Sentai, considering that his name would fit in perfectly with that seriesnote Gaoranger's monsters of the week all follow the naming pattern of "___ Org".
Honami initially thought Ayase (Time Blue) was Time Yellow. In Power Rangers Time Force, the actual Time Yellow, Domon's, womanising traits would be given to Lucas, the Blue Time Force Ranger.
"Case File 10: The Escape To Tomorrow": Mercenary Org is a dangerous mercenary dispatched by the Londerz Family to eliminate the Timerangers, who combines frightening brawn with deadly brilliance. First using a space-time communication pulse to lure TimeRed and TimeBlue into a trap and disable their Chrono Changers, Org detonates a bomb to try and kill the two, even returning to the scene to ensure his targets are dead. When he discovers they survived, Org uses his memory of the battlefield to drive the two into a freezing room, trapping them to let them freeze to death as he fights off TimeYellow and TimePink. When Org is narrowly foiled by TimeGreen with the four Timerangers on the brink of death, he turns himself giant for a last shot at the bounty, finally being defeated after charging TimeRobo Alpha.
"Case File 14: Dead Heat:" Mad Racer Baron is the former racing rival of Ayase. After Ayase turns him in for a crime, Baron crafts a new plan in prison. After being released, Baron plays the role of a getaway driver for the Dolnero crime family, pretending to be madly in love with Dolnero's moll Lila, all the while hunting down Ayase, who has become TimeBlue. Fearless and cunning, Baron repeatedly helps the Dolneros escape crime scenes, eventually slipping away via disguise and challenging Ayase to their final race, convincing Ayase to do so. When Ayase rams his car and disqualifies himself from their race to save children, Baron willingly turns himself in after acknowledging that Ayase had the moral high ground and tells off Lila for her criminal ways. Even when Lila brainwashes him as a last resort, Baron admits that he was secretly jealous of Ayase all along, before breaking the mind control with his willpower and ensuring his own arrest at the hands of his rival.
"Case File 15: Search for the Sniper": Sniper Reihou is a capable assassin dispatched by Don Dolnero to eliminate the Timerangers. Immediately demanding more pay from the Londerz family in exchange for the Timerangers' deaths, Reihou begins her pursuit by tracking down the Timerangers' ally Honami. Interrogating her and disabling an elevator to avoid interference, Reihou uses a single picture from her wallet to deduce the home of the Timerangers. Putting a bomb collar upon Honami in an open square, Reihou draws the Timerangers out and splits them up. After they are in the open, Reihou nearly manages to eliminate them, even using their honor to falsely surrender and escape once tracked down, summoning backup and turning gigantic, before shooting Yuuri while gigantic. Reihou holds her own against Time Robo before finally being brought down and freeze-compressed.
Gien crosses it by killing Dolnero in cold blood. Showing once and for all the lovable child that Gien once was is no more.
Captain Ryuuya crosses it by not only trying to have the past century destroyed so he could save himself, but also by actively engineering Naoto's demise at the same time so he could make sure he himself wouldn't die.
Masaru Nagai would later go on to portray Master Black.
Signature Scene: In episode 31, where Naoto throws his hat as his theme starts right before he transforms. Even people who haven't seen Timeranger know about how awesome that moment is.
Gien's backstory. He used to be an uneducated human boy who befriended Don Dolnero, was tortured and nearly killed by Dolnero's rival Kronz Family, and had his brain transferred into a robotic body in an effort to save his life, only for the process to drive him increasingly insane.
The ending! Don Dolnero tries to stop his old friend Gien, now completely insane, only to find he can't do so and is killed by Gien as a result; the team saves time from collapsing on itself, but their Sixth Ranger dies and four of the Timerangers have to return to the future, separated from their surviving teammate.
Naoto's death. Shot in the chest on the orders of Captain Ryuuya (who'd caused him to become TimeFire in an effort to avoid dying himself) and falls off a roof as a result, dying in Tatsuya's arms.
Too Cool to Live: Naoto. Tatsuya's rival and easily one of the strongest rangers ever. Although he was tragically killed as a result of Ryuya's manipulation, Naoto paid no heed to his own demise and instead gave Tatsuya the V Commander to end the Catastrophe plaguing their world.
The Woobie: Yuuri and Sion. Yuuri lost her family to an assassin sent by Don Dolnero (only to find he didn't even remember doing so when she told him about it in his dying moments), while Sion is the only one of the four whose history was not changed for the better by their actions, meaning he's still the Last of His Kind and was kept in a lab as a test subject.
