Good point, but it's not a "slip up" so much as a necessity for the movie production. Meatloaf Aday who played Bob (Robert Pulson) had recently lost a lot of weight, and as the character was supposed to be huge they had to use a fat suit to make him appear...huge.
The t-shirt was to cover the fat suit.
However, the story (book/script) would have bob shirtless.
It is also a possibility that the director didn't want to have 'Bob' topless in the movie because of what is under his top. While ok to read about and see under a shirt, you never really know how an audience will react to exaterated male breasts..not to mention keeping a decent rating on the film.
Hey, I thought the point was that Bob had bigger T#$#s than Marla, and nobody would fight him shirtless due to the extreme danger of being boob whapped(ouch)
Yes... but also, in both the novel and the movie it is mentioned that Bob has breasts, like a woman almost, so therefore he would be excused from the shirt rule, no? It's almost a common courtesy thing.