Time for a Sonic Adventure fun fact. The bats of Red Mountain are broken in the final game. The bats of Act 2 have 4 different paths of flight that each choose randomly when approached by the player:
>Midpoint between the Player and the Bat's initial position
>Go to Player (Or more accurately, under their feet since it doesn't account for height, seen in the gif and screenshot)
>Go to Camera (seen in Gamma's gif)
>Do nothing (Briefly flies and then goes back, also used as an idle behaviour)
They hardly move when encountered in-game in the final due to an error in calculating their next path. Understanding this error requires knowing about another (Unseen) piece of the bats' behaviour:
Every 10 frames, the bat checks its position and resets if it's >= 100 units from its initial position. Due to the bat's behaviour in-game, this limit is impossible to see, but it can be seen in the Announcement footage (see the gifs).
The check for this seems to have been copied when the other paths were added to retarget the bat when it reaches its destination, without inverting the range check or removing the 10-frame wait. This results in their current behaviour - every 10 frames, the bats check whether they are >= 0.2 away from the player, and if they are, they choose a new path.