Line the bottom and sides of a 9-inch round cake pan with long pieces of plastic wrap. Whip the cream to stiff peaks in a large bowl with a mixer. Slice the bananas about 1/4 inch thick.
Spread one-third of the whipped cream on the bottom of the pan. Cover with half of the banana slices in concentric circles, then top with half of the animal crackers in concentric circles. Repeat with another layer of whipped cream, bananas and crackers. Finish with the remaining whipped cream. Wrap up the cake and refrigerate overnight to let the crackers soften.
To serve, unwrap the cake and invert it onto a plate. Thinly slice the remaining banana. Garnish the cake with the banana slices arranged around the edge and a few animal crackers in the middle.