  We study experimentally and numerically the quasi-bidimensional transport of
a $^{87}$Rb Bose-Einstein condensate launched with a velocity $v_0$ inside a
disordered optical potential created by a speckle pattern. A time-of-flight
analysis reveals a pronounced enhanced density peak in the backscattering
direction $-v_0$, a feature reminiscent of coherent backscattering. Detailed
numerical simulations indicate however that other effects also contribute to
this enhancement, including a "backscattering echo" due to the
position-momentum correlations of the initial wave packet.
