Animation overflow glitch

The animation overflow glitch is a type of error affecting all known versions of Speedy Blupi and Speedy Blupi 2, to varying degrees of severity. In Speedy Blupi, the bug causes graphical corruption on many entities. This was almost entirely fixed in Speedy Blupi 2. The bug is caused by playing a level for an extended period of time.

Entity animation overflow
The bug is caused by an integer overflow in the animation counters of dynamic entities. Entities use 16-bit signed integers for their animation counters, which have a range of -32768 through +32767. Many of these counters start at 0 and increment every frame, thereby overflowing after 32768 frames have passed. At the default 20 frames per second, these animation counters will take 27 minutes and 18.4 seconds of in-game time to overflow (13 minutes 39.2 seconds in double speed mode).

Fix
This bug was mostly fixed in Speedy Blupi 2. Rather than the animation counters overflowing to -32768, they are reset back to 0 after reaching their maximum value. This causes a noticeable "stutter" as entities suddenly jump back to their first frame of animation. However, with no lasting effects, the bug is much less severe.

Blupi animation overflow
A more obscure variant of this bug can affect Blupi's animations as well. Blupi's animation counter uses a 32-bit signed integer, which has a range of -2,147,483,648 through +2,147,483,647. At 20 frames per second, this counter takes approximately 3.4 years to overflow (1.7 years in double speed mode), given that no player input is given within that time.