To finish the face of your miniature felt mouse you need to add the mouth, nose, eyes, and whiskers.
For the nose and mouth, color the nose of the mouse with the same soft pink or orange you used for the inside of the ears. Don't make it too bright. Use dark brown or black embroidery or sewing thread and stitch on either side of the nose, then down a bit of the underseam of the face as shown. If you wish you can give the mouse the effect of a smile by making two small stitches back from the stitch on the underseam, going out slightly on either side of the face.
For the whiskers, use a silk embroidery floss or fly tying floss and take a stitch to anchor the floss on either side of the face just in back of the nose. Separate the floss with the end of a pin, and trim it to the correct length for your mouse's face.
To make the eyes, take a stitch intot the face where you want to place an eye and then sew a small bead to the face. If you are making a mouse for a child, use large french knots in embroidery thread for eyes instead of beads, and don't use a wire armature for the mouse. Once you have one beed or knot in place for the eye, take your thread through the face to the other side, and add the second bead or knot, drawing up the thread between the two eyes to pull the eyes into the face to give it some shape. Take the thread for the eyes out the back of the head at the seam, or under the head at the seam and tie the thread off, clipping any loose ends.