
Fair Fight - S6-E5
Continuity mistake: When Johnny and Roy are in the ER after the cave-in rescue, while they're talking to Dixie and Brackett, we can see how long Johnny's hair is. After they get back to the station, when the guys decide to name the dog Henry, there's a closeup of Johnny and now his hair is much shorter and even layered at the sides. Additionally, the dirty areas on his shirt change.

Fair Fight - S6-E5
Visible crew/equipment: At Rampart, when Dr. Bracket, DeSoto and Gage are discussing the Hubbards while walking down the hall, two T-marks become visible on the floor behind them when they turn the corner.

Fair Fight - S6-E5
Visible crew/equipment: After the cave-in rescue, when Dixie, DeSoto and Gage are in the ER, Gage washes his face and as he comments that he wasn't cut out to be a mole, two tape marks are visible at his feet.
Answer: I believe you are speaking of the old man, Mr. Wilson. He's played by J. Pat O'Malley.
Bishop73
Correct, it was J. Pat O'Malley...he also played the grandfather with his grandson when their rocket exploded, and also played "Old Bill" in the episode with Ann Prentiss, where Gage saves the little girl from the burning tree house, and her mother falls in love with him.