It depends on what you consider "significant". Do you mean significant from a plot perspective, or significant from a motion perspective?
There are a total of 14 true animatronic figures in TBA (grand total including all duplicates, and these are all returning characters from the film), ones that have good to great range of motion that is also dynamic and non-repetitive. There are an additional 32 new instrument playing critter figures in the ride in total (16 individuals, but duplicated twice so they reappear in the finale). However, these 32 figures are extremely rudimentary. They only have 1-3 joints each. The turtle, one of the bobcats and two of the large bears for instance only have a single axis. None of the 32 critters have any motion above the neck, no eye or mouth movement. Their movement is also the same one-two-one-two back and forth pattern repeated over and over again forever. Nothing dynamic or synchronized to any sort of audio source (even the ancient Tiki Room birds put them to shame). For reference, the relatively "simple" squatting bullfrogs AA's in Splash could turn, blink, bob their heads and torsos, and open/close their mouths. All programmed to synchronize with the music and lyrics being played back. They could visibly talk and sing. Nothing looked repetitive.
With that baseline established, Splash Mountain at WDW had roughly 55 of these true animatronic figures. The simplest of which were the aforementioned squatting bullfrogs and the Mr Bluebird and Brer Roadrunner figures. Even these are still much more complex than any of TBA's new critters. The larger and more complex figures are actually still quite impressive to this day, in fact they actually still move better than four of the legitimate AA's in TBA (Charlotte, Eudora, Naveen and Ralphie I believe don't have any mouth movement).
^There were a substantial number of these large complex figures (and remember that their mouth movements were in sync with vocals). That finale scene alone in its entirety had about 17 characters of this caliber. There's something like 20ish other AA's scattered through the rest of the ride which were similarly complex (including the main Brers along with other secondary critters). So over 35 in total of these larger advanced AA's. But again that isn't including any of the bullfrogs or birds, which again are still "true" AA's in the sense that they have a decent amount of axes of motion. Programmed in a dynamic manner Including head turns/nods, blinking and mouths opening/closing in sync with recorded music/dialog. Of course, there were a fair few simpler moving props as well that i'm not including among this total. Spinning beehives, giggling fountain riding turtles, tiny hanging possums, a couple Brer Bears etc. I'll also note in passing that the entire riverboat itself also tilted back and forth, and the waterwheel would spin.
At Tokyo, you can add another 5 to the total of large complex AA's in addition to what WDW had, so about 60. They got a few extras from California that were missing from WDW's.
California's version had the most true AA's of the three Splashes. It inherited an additional handful from America Sings that weren't replicated in the other two versions. About 75 true AA's in total by my count. My count is ever so slightly less precise here because DL's is faster and has more to count (with fewer walls between the intertwining scenes), and I unfortunately never had the opportunity to ride it in person either. Nevertheless, over 70 genuine AA's. And a greater amount of large and complex ones too since it had additional geese, storks, dogs, cats, donkeys, wolves etc. Again not including the simple static or basic moving props of course. The finale scene alone had 26 large complex AA's. And their riverboat also used to tilt as well.
