Using Swedish 1 m Solar Telescope Crisp Imaging Spectro-Polarimeter 6563 Å (Hα) observations and MANCHA3D simulations, we analyze the formation and evolution of falling knots beneath a hedgerow prominence. By comparing the observed knot widths and kinematics to those of a parametric survey of simulations, we estimate the range of magnetic field values and characteristic wavelengths to test if the magnetic Rayleigh–Taylor instability (MRTI) can provide a physically meaningful explanation. We recover observational parameters using a novel semiautomated method and find knot velocities with a mean of ‑9.68 km s‑1 and a mean width of 614 km. Our simulations survey a range of critical wavelengths, λ c , of 100 to 500 km, and magnetic field strengths, B 0, of 1 to 20 G, finding the closest match to observations around λ c = 300 km, and B 0 = 2 to 6 G. As both the observational and simulated values match expected values, we conclude that the MRTI can provide a physically meaningful explanation of this observation. Additionally, we also predict that the Daniel K. Inouye Solar Telescope will be able to observationally recover secondary instabilities on the leading edge of the falling mass through applying a point-spread function to an example from the simulated results.