The compound & manor housing the secret weapons lab is the same location used in Magnum, P.I. (1980) as the Robin Masters Estate, The Robin's Nest. Comments by characters in the Magnum, P.I. series reference 5-O and McGarrett, confirming these two shows are in the same multiverse.
The assault rifle used by Wo Fat (Khigh Dhiegh) and the Red Chinese (Valmet M76) is a derivative of the Soviet Kalashinkov (AK47 and its variants).
Last show of the series.