Yeah, by "bulge" was probably the wrong word. I didn't mean it needs proper physics. A shake animation for the whole goal + a nice sound effect is probably good enough and more fitting with the rest of the graphics. Definitely not fireworks or confetti for each goal (that's something that would be fitting when you win the world-cup or something).
Regarding Tennis+OtherMechanics - the Virtua Tennis series had some great mini-games mixing Tennis with many other mechanics along it's various iterations. Question is to find one that is fun for longer than just a "mini-game".