Bug: When Josh asks you by phone to meet Amber and her other rather available friend, the screen is not locked, so you can change screen and avoid replying him entirely, but the game treats it as if you did and you are meeting him anyway. The option to reply through the phone is still there anytime days later, obviously to no effect. Normally the game forces you to reply before you can move forward.
Bug: Get on the dragon fountain in Barcelona, jump on the water coming out while off your board (do not walk), and do a grab trick (and hold it) you will be doing tricks on the ground.
Bug: (Frisbee Golf) If your Wii Motion Plus accessory doesn't respond while throwing a Frisbee, the Frisbee (along with your Mii's hand) will spin around the Mii's body.
Bug: In one of the most inexplicably frustrating bugs in videogame history, when you beat the game in Championship or Tournament mode, the ending does not load, and you are simply brought back to the title screen. The ending does exist, and it's viewable through cheat engines such as Action Replay.
Bug: When viewing the starting point's properties, it is possible to lock it to the driving line. If it is locked and physics is turned on, leaving the shack that normally provides the boundaries in the editor is possible. This is likely the reason for why it is not able to be locked to the driving line in the game's sequels.
Bug: Kingdom of the Crystal Skull, Part 2: In the opening location, there is a bus and a biplane. Have the character fly off in the biplane and instantly parachute down and place the bus in the precise location of where the biplane was on the hangar. Once the biplane returns to the hangar, it will crash into the bus and possibly send it off flying into the air. When the bus stops and jumps back up, the bus will then be floating in the air and can then be driven whilst floating through the air.
Bug: I always thought I just imagined things back in the day when coming out of the hallway's window door I saw a statue randomly flying across the screen. I was never able to replicate the bug, but it turns out it actually is a legitimate bug with an explanation (it was supposed to be an airplane Easter egg, but the code fetches the wrong item). Longer explanation and even a fix in the video.
Bug: Within the game, some classes are able to use firearms such as pistols and rifles. Muzzle-loaded pistols and rifles make up the majority of these arms, yet you can fire with them on full auto without having ever to reload.
Bug: In the mission "Breaking and Entering" if you go into the ladies' restroom and look in the mirror, two stall doors are always seen as open.
Bug: The main character has to deal with a rather defiant coworker at the beginning of the game, detective Lowry. Lowry in particular constantly defies the laws of physics, since he sits with his butt hovering about 6 inches above his seat.
Suggested correction: This might not even be a bug at this point. The image of Lowry here is even featured by the developers on the product page.