Rehabilitation robotic devices are used to enhance the physical capacity of individuals, yet frustration and pain from repetitive tasks often lead to dropout during physical rehabilitation. Mixed Reality (MR) can be used with these devices to offer engagement and motivation. However, further investigation is needed to understand the full effects of MR in rehabilitation. This paper presents a case study analyzing the effects on gait kinematics and the presence of adverse symptoms using a Smart Walker in an immersive MR scenario. The results indicate only slight differences with MR, such as a stride length that is 0.05 m lower compared to walking without MR.