Determining something to be "remarkable" is subjective (meaning one's determination of what is considered remarkable differs for individuals). Therefore, some readers may disagree with the answer provided.
The remarkable thing about the narrator's mother in Louise Erdrich's "The Leap" is the fact that she was a trapeze artist. Knowing that she spent a portion of her life flying through the air is utterly remarkable. Even more remarkable that this is her attempt to complete a stunt where she would perform blindfolded. Although this act did not end well, her attempt alone is remarkable.
As her life continued, she would continue to make "leaps." After losing one child, she successfully raised another. After losing her eyesight, she was able to carry on as if nothing happened. Most remarkable, her child recognized that her mother gave saved her life three times. This is utterly remarkable.
According to eNotes, the narrator's mother, Anna, is "the surviving half of a blindfold trapeze act." Anna is also a hero, as she saved the narrator's life when their farm house burned down. For other events of Anna's past, you might want to look at the rest of the summary provided by eNotes. I've posted the link below.