This article lists undocumented changes that have appeared in Patch 2.4.0.
General
Dwarf male shoulder pads have decreased in size, and weapons have increased in size.
Some items equipped by tauren look smaller when worn over the shoulder than they do when wielded in combat.
Players in Thunder Bluff are no longer auto-dismounted if they travel through buildings to other parts of the city. Druids won't lose their [Travel Form].
Game physics have been changed to prevent wall climbing.
Battleground matchmaking for premades has been tightened, so it is more likely that a premade will meet a group with similar gear. This can result in longer queue times for premades.[2]
[70G3 Daily] The Deadliest Trap Ever Laid (Aldor) or [70G3 Daily] The Deadliest Trap Ever Laid (Scryer) have had their gold reward increased to 18 gold, 28 silver; from 7 gold 28 silver.
Quests giving players Stormpike Insignia or Frostwolf Insignia had their level adjusted for level 70 players. As a result each trinket upgrade will additionally give 11 gold, 40 silver at level 70.
Druids that were in [Moonkin Form] or Tree of Life Form will now be able to auto-shift out to mount up. This now means that costumes can't be used to have Moonkin mounted.
[Moonkin Form] is now affected by the Fel Orc Costume buff.
Hunter
Ammo Pouches and Arrow Quivers can no longer be simultaneously equipped in your character's bag slots.
Pet threat/aggro generation is acting differently than it did in Patch 2.3.3. See this bug report for more information.
[Snake Trap] itself and snakes summoned by its trigger no longer despawn as soon as hunter dies (similar to all others traps).
Mage
The absorb values of [Ice Barrier] have been increased.
Touch of Weakness no longer interrupts channeling when it procs.
Mind Vision can no longer be used in Arena. It also doesn't interrupt drinking/eating.[4]
Rogue
[Cheat Death] now properly reduces incoming damage (was bugged since 2.3.2 patch: it decreased all incoming damage by 90% and then absorbed 90% of damage taken. In reality, it should be 99% of all damage absorbed for 3 seconds). Also the passive ability now has a large animation under the rogue's head upon trigger.
Shaman
The Clearcast buff no longer has a sound effect. This is a known bug.[5]
Items intended for Retribution paladins have been rebalanced. Spell damage has been replaced with stats such as critical strike, haste, and strength on Season 1 and 2, Tier 4 through Tier 6, and other miscellaneous Retribution gear. Season 3 was already changed in patch. 2.3.
Stats of [Shifting Tanzanite] changed from +5 Strength +4 Agility to +5 Agility and +6 Stamina.
Corrected tooltips for most trinkets to show more accurate cooldowns (only tooltip text change). For instance, [Bladefist's Breadth] now show correct cooldown of 1.5 minutes instead of 2 minutes.
Items with cooldowns now have text "Cooldown Remaining: mm:ss" at their tooltips.
Engineering Dragonlings now have a 20 minute cooldown instead of 1 hour.
Mob level of engineering crafted defensive pets are no longer linked to engineering skill. (At 375 engineering, Battle Chicken down from level 72 to 40, Mithril Dragonling from 72 to 40, Arcanite Dragonling from 72 to 50). [3]
[Mystical Skyfire Diamond] No longer has a 2% chance to reduce the next spell's casting time by 50%. Now the 1ppm "Focus" buff lasts for 4 seconds and Increases Spell Haste Rating by 320. The buff still has a 45sec internal Cooldown, but is no longer consumed.
The quest item that leads to Jaguero Isle has had its level requirement reduced to level 42, to be in line with the dropped level of the quest and island from at patch 2.3.
[Stratholme Holy Water] now does less damage. Most likely due to not being affected by Spell Damage.
[Fiery Festival Brew] now makes you a little tipsy and shoot flames out only for a few seconds. Previously flames would come shooting out of your mouth for about 10 seconds. There is also a duration (14 days).
Item stats in item tooltips are no longer sorted. Previously white stats always appeared in standard order of Strength, Agility, Stamina, Intellect, Spirit, now they may appear in any order. Green stats were also sorted and aren't any more.
All Whelplings and Frog companions now play a sound when clicked.
Instances
The size of Supremus in Black Temple has increased significantly. Also, the hitbox of Supremus has been reduced significantly.
The area around Archimonde in Battle for Mount Hyjal has been decreased in size and players are no longer able to go into the hills around his area. Also, the hitbox of Archimonde has been reduced significantly.
The Prince Malchezzar fight in Karazhan has had its safe spots on the left side of the room removed as of 3/26/08
Tempest Keep - Al'ar - Flame patches in phase 2 can no longer be killed with spell reflect by warriors. Al'ar's hit box was made smaller.
User Interface
Tutorial hints (after clicking on the yellow exclamation mark at the bottom of the screen) are now displayed in the center instead of at the bottom.
Raid Window in default Blizzard UI will no longer become empty or locked if opened during combat.
Raid target icons (the skull, cross, circle, square, etc) can now be shown in chat by enclosing their name in "curly brackets" - for example {circle} or {skull}
Bug fixes
The Falthrien Academy is now correctly displayed as a subzone of Eversong Woods, not as a zone (which has a bigger fade text on entering).
The capitalization of the Valley Of Heroes has been changed to Valley of Heroes.
Some mounts (like the epic Hawkstrider) now make a sound, when standing still and pressing the space bar. There has been an animation. Tiger mounts however, no longer make a sound.
Wind Rider Master Urda, in Hammerfall, is now standing on her platform instead of under it.
The cost of flight paths and repair will now be properly reduced if your reputation is Friendly, Revered or Exalted.
Vanndar Stormpike and Drek'thar no longer give info about how many elite NPCs are left at Alterac valley (these elites were mostly removed in patch 2.3).