In this movie, Rika sings. Surprisingly, that's not the reason this one isn't canon.
Strictly speaking, only the second Adventure movie is canon, and only because it was directly referenced in Zero Two. The dub added a few too many inconsistencies to the first movie, while the first entries for Zero Two and Tamers would be difficult to synchronize in each respective series (just because Willis and Kai were proven to exist doesn't mean we have to assume that Davis and Takato had adventures with them in the exotic lands of Colorado and Okinawa). The second movies for these (and, to a much less egregious extent, the Frontier movie) are even more problematic in that they act as though each series did not end the way they did.
Why does Revenge of Diaboromon get a pass on this while it's a nagging flaw for Runaway Locomon? For starters, compare the endings of Zero Two and Tamers and tell me which one's more forgivable to ignore. It's also very easy to accept the idea of the Zero Two kids (and only the Zero Two kids) running around with their Digimon in the real world because there was plenty of time in the series where that was the norm. Even though the movie apparently took place after the ending, making it totally wrong, we don't have to make a big adjustment.
This movie clearly takes place after the ending, as there was never a point where Kenta and Kazu had partners in the real world, but Jeri didn't (and wasn't catatonic in a pink bubble). That means that for us to accept the reality of this movie, we have to make some very strong presumptions about the meaning of an ambiguous ending. We saw a little data packet offering Takato a glimmer of hope that contact might be re-established... then suddenly all the Digimon are back and hamming it up. We don't even get an emotional reunion; everything's just instantly butterflies and rainbows. No part of the Tamers ending suggests butterflies and rainbows. That's the Zero Two ending. And look how that one turned out.
As to the content of the movie itself, it feels like the writers are using this last adventure with the Tamers cast to set these characters free, unchained from all the theme and story and psychology that made the series what it was. There's nothing wrong with a curtain call, but half the movie is spent making sure everybody from Beelzemon to MarineAngemon to Justimon get screentime. Most of the movie's humor is in the way all these players stumble over each other, making the operation twice as difficult, but it's hard to build a decent story around that.
Instead, we get Speed 3: Flakes On A Train. A Parasimon possesses a Locomon to chug around Tokyo in order to open a vortex to unleash its brethren. Yamaki comes up with a solution instantly, but Takato and Rika decide to utilize a more hands-on approach, which fails so hard, wastes everybody's time and results in Rika getting possessed herself and attacking Takato with a wrench. Somehow, this is the best part of the movie.
It's all worth it to see Rika's daddy issues though, right? The dub does do an exceptional job taking the message of Rika's song and her lip flaps and writing a whole new song around them (it helps that Rika's voice actress can really sing). While it's an interesting peek at her past, it has nothing to do with anything. All we learn is that she misses her daddy... and she doesn't care much for birthday parties. There's no resolution here. While it's amusing to see Takato forced to play her psychiatrist instead of Renamon, it's ultimately Guilmon who knocks her out of it with a well-placed fireball. In the end, she still misses her daddy.
Apparently, she also still doesn't care much for birthday parties. Which is a strange final note to end Digimon Tamers.
My Grade: C+
- Notice that Takato is trying to keep Guilmon under wraps, yet they spring into action the moment there's trouble afoot... even before discovering that the train's a Digimon.
- For this movie, Philece Sampler voices Riley. Now, while I don't usually comment on new voice actors who have to fill in for these movies (Jeri, Lopmon and MarineAngemon were also replaced), it amuses me greatly that Riley went from having Yolei's voice actress to Cody's.
- Yamaki calls Rika in order to talk to Takato, as if he knew they'd be on the train together. Also, despite him designing the algorithm that saved the goddamned world, Rika doesn't trust Yamaki. This is the rug for all those fans pulling for the crazy theory that Yamaki was Rika's dad. It would be pulled later in the movie.
- When I say that Melissa Fahn can sing, I mean she can sing. Just as Davis did for this series, Rika served as narrator for Frontier. She was replaced towards the end so Fahn could be in Wicked. And when I say “be in Wicked,” I mean she's on the original cast soundtrack.
- Yamaki ordered modifications to the tracks in order to divert Locomon's path. What he meant was “build an entire new track to link up two separate tracks that didn't originally connect that way, and do it now!” Those builders are the real heroes!