I looked up Kerry Wood's 20K game to verify that he didn't strike out 8 in a row (7 was the most). I then stumbled across some interesting tidbits. Retrosheet.org has a section on "lost home runs".
6/30/1969: At Parc Jarry in Montreal, in the top of the second inning Ernie Banks of the Cubs hit a ball to right field that cleared the fence but was difficult to see in the bad lighting. Expos right fielder Rusty Staub kicked some dirt around and convinced the umpires that the ball went under the fence. Cubs manager Leo Durocher argued the call and was ejected. He then protested the game, won by the Expos, 5-2. This homer would have been #488 for Banks, who finished his career with 512 four-baggers.
We all know Ryne Sandberg lost a HR when the first night game at Wrigley Field was rained out. Did you also know:
5/28/1990: In the bottom of the third inning at Wrigley Field, Ryne Sandberg hit a two-run home run just inside the left field pole that third base umpire Bill Hohn ruled a fair ball. However, Giants manager Roger Craig came out and argued the call. After a discussion by the umpires, crewe chief (and first base arbiter) Harry Wendelstedt overruled Hohn and called it a foul ball. Television replays clearly showed it to be a fair ball and a homer. Cubs manager Don Zimmer was ejected because of the changed call. Sandberg singled but the Cubs did not score in the frame but eventually won the game, 5-1.
I also did not know that "Courtesy Runners" were allowed until 1950. For example,
6/4/1915 (White Sox at Red Sox) - Tris Speaker was hit on the head by a fast ball in the first inning and, after walking slowly to first, was replaced by Bill Rodgers. Speaker played in the field in the next half inning but then left the game in favor of Olaf Henriksen. Rodgers pinch hit for another player in the eighth inning.
9/28/1947 (Cardinals at Cubs) - Bill Nicholson tore up his shoe sliding in the 4th inning. Pitcher Hank Borowy went in to run and eventually scored as Nicholson went for a new shoe. Nicholson returned to RF in the top of the 5th.
Courtesy Fielders were also allowed.
9/1/17 (Tigers at Indians) - (COURTESY FIELDER) Tris Speaker was on 3b in the bottom of the first with Joe Evans at bat. Tris tried to steal home but Evans hit away and lined a ball into Speaker's face. Detroit manager Hughie Jennings, as a courtesy, allowed Tris to sit out in the second inning while his face was sewn up. Elmer Smith played cf in the top of the second and Speaker went back in for the third.
And the very last one on the list involved the Cubs.
8/10/1952 (Cubs at Pirates, game 2) - (COURTESY FIELDER) In the top of the ninth of the second game of a twin bill, Pirates catcher Clyde McCullough was injured and could not continue. The Pirates two other catchers, Eddie Fitzgerald and Joe Garagiola, had already been used in the game as pinch hitters. With the approval of Cubs manager Phil Cavarretta, Fitzgerald was allowed to replace McCullough. The Cubs won the game 4-3. Under the playing rules in effect since the 1950 season, that was an illegal substitution that the umpires should not have allowed.