In the original Anaheim Disneyland it may be a Small World after all, but that world’s inhabitants are getting bigger and heavier almost by the day, so much so that some of the rides may have to be re-engineered. This has already been scheduled for the Small World ride, which will be closed for almost a year beginning in January for retooling.
The problem, quite simply, is that the flume that the boats ride in, and the boats themselves, were designed and built in 1963 on the assumption that the male adult riders would average 175 pounds and the women about 135, which they pretty much did at the time. Alas, those figures are as outdated today as the Rocket to the Moon ride.
The Small World ride now must accommodate adults who frequently weigh north of 200 pounds, which it often cannot do. Increasingly, overweighted boats get to certain points in the ride and bottom out, becoming stuck in the flume.
— Larry, Attack Mickey, Light Reading