“Stuart Little,” starring E.B. White’s charming white rodent, grossed $11.5 million since Friday and remained the top weekend movie for the second week running, and “Fantasia/2000,” featuring Mickey Mouse, posted elephantine numbers in limited release, according to industry estimates. “Fantasia,” playing in only 54 IMAX theaters in North America, boasted a phenomenal per-theater average of $50,000 (that’s compared with $3,860 for “Stuart Little,” playing on 2,979 screens). Elsewhere in the weekend rat race: