We study the bursting dynamics of a thin oil film sandwiched by glycerol aqueous solution in a confined geometry where the circular symmetry of the bursting hole is broken. We find that the bursting proceeds with a constant velocity except for initial times and the velocity is governed by the viscosity of the surrounding glycerol. Different from previous studies where the bursting speed is constant, in our confined geometry no rims are formed at the bursting tip as a result of the symmetry breaking. Our findings can be explained by original and simple scaling arguments.