High Diving Hare

Bugs Bunny is drumming up business for a vaudeville show in a remote western town (notably one of the posters in the background is for "Frizby the Magician", a reference to director Friz Freleng). One of the main attractions is "Fearless Freep" and his high-dive act. As soon as Yosemite Sam hears the name "Fearless Freep", he goes into a joyful frenzy, buying as many tickets as he can. ("I'm a-splurgin'!")
During the show, as Bugs is about to introduce Freep, he gets a telegram informing him that Freep is delayed by a storm and won't be able to appear until tomorrow. An angered Sam insists on seeing the high-diving act and forces Bugs at gunpoint to the top of a high-dive platform. But Bugs manages to pull out all his tricks and stops, and it is Sam who does all the diving, in a different comical setting nine separate times (in a variant of the diving act from "Stage Door Cartoon").
1: Sam pushes Bugs to the edge of the platform (with Bugs baring his claws to secure himself to the board). Bugs tells Sam to cover his eyes while he puts on his bathing suit, and then proceeds to spin the board around so that Sam is at the diving edge. Bugs makes it look like he's taken the dive (accompanied with an audible "SPLASH"), while Sam turns around and starts to walk off, right off the edge and into the tank, which falls apart with the water still intact after the hoops break off the tank when he crashes in.
2: Bugs springs on the board so hard that he sends Sam up, over his head and down (separating Sam from his pistols in the process). Bugs then realizes that he forgot to fill the tank with water, so he grabs a bucket of water and throws it down from the diving board past Sam. The water makes it into the tank, but Sam misses the tank altogether, smashing through the stage into the basement.
3: Sam walks to the end of the board and finds Bugs standing on the board upside-down ("Great horny toads! What are ya doin' down there upside-downy?"). Bugs points out that it is actually Sam who is upside-down ("I'm not upside down, doc. You are! Look!"). Sam looks "up", sees the tank, and falls into it.
4: Having been verbally hit with "fightin' words", Bugs dares Sam to "step over a line" (in a gag similar to one from Bugs Bunny Rides Again), sending Sam down for the splash again (but not before springing back up for a moment to declare: "I hate you!")
5: Sam is stopped by a door, and yells "Open up that door!" then turns to the audience and says: "You notice I didn't say Richard?". He backs up and charges towards the door, which Bugs opens at the last moment, leading Sam to another splash, this time assisted by an anvil given to him by Bugs.
6: Bugs, dressed as an Indian, points Sam to a "short-cut" in a desert-like setting ("Quick! Him go that way! You take-em short cut! Head him off at pass!"). Sam thanks the "Indian" and takes the route, leading to yet another dive.
After two more dives in which the setups are unseen, Sam finally has Bugs tied and standing on the edge of the platform, with Sam sawing away at the board, gloating: "Now ya smarty-pants, let's see ya get out-in this one! This time, you're a-diving!" However, as soon as Sam cuts through the board, it's the ladder and platform that falls, leaving the cut plank suspended in mid-air. Bugs turns to the camera and cracks: "I know this defies the law of gravity, but, you see, I never "studied" law!"

Question: What broke off the tank?
Answer: The hoops broke off the tank.