What are some warning signs of bowel perforation? especially if it's minor, like a small hole or tear?

Abdominal pain : It all depends whether it is stomach, small bowel or large bowel. Most of them will present with a quite severe abdominal pain, nausea, vomiting, fever in an otherwise healthy patient. Most of these patients will end up in the hospital quickly due to the pain. The symptoms may be much les prominent in an immunocompromised patients.