In the equilibrium of forces lab using spring scales, potential sources of error include inaccuracies in the spring scales, misalignment of the strings, and variations in the tension applied. Friction can affect results by introducing additional forces that may skew the readings, leading to incorrect conclusions about the equilibrium state. Environmental factors, such as temperature changes, could also impact the performance of the spring scales. Ensuring proper calibration and alignment can help mitigate these errors. Accurate data collection is essential for reliable results in this experiment.