Preheat the oven to 375 degrees . Arrange the bacon on a broiler pan; bake until crisp, 15 minutes. Let the bacon cool, then reserve 8 slices and finely chop the rest.
In a medium bowl, stir together the chopped bacon, cream cheese, scallions, radishes, carrot, celery, red pepper and garlic.
Slather the bagel bottoms with the cream cheese mixture. Top each with 2 slices bacon, 2 lettuce leaves and a slice each red onion and tomato. Season with salt and pepper and add bagel tops.