diff --git a/src/ai/api/ai_industry.hpp b/src/ai/api/ai_industry.hpp
index bf93cd4669..da27ec9207 100644
--- a/src/ai/api/ai_industry.hpp
+++ b/src/ai/api/ai_industry.hpp
@@ -86,7 +86,9 @@ public:
 	static TileIndex GetLocation(IndustryID industry_id);
 
 	/**
-	 * Get the number of stations around an industry.
+	 * Get the number of stations around an industry. All stations that can
+	 * service the industry are counted, your own stations but also your
+	 * opponents stations.
 	 * @param industry_id The index of the industry.
 	 * @pre IsValidIndustry(industry_id).
 	 * @return The number of stations around an industry.
diff --git a/src/ai/api/ai_vehicle.hpp b/src/ai/api/ai_vehicle.hpp
index 6d15a8cef8..bc2360b407 100644
--- a/src/ai/api/ai_vehicle.hpp
+++ b/src/ai/api/ai_vehicle.hpp
@@ -422,11 +422,12 @@ public:
 	static bool SellWagonChain(VehicleID vehicle_id, int wagon);
 
 	/**
-	 * Sends the given vehicle to a depot.
+	 * Sends the given vehicle to a depot. If the vehicle has already been
+	 * sent to a depot it continues with its normal orders instead.
 	 * @param vehicle_id The vehicle to send to a depot.
 	 * @pre IsValidVehicle(vehicle_id).
 	 * @exception AIVehicle::ERR_VEHICLE_CANNOT_SEND_TO_DEPOT
-	 * @return True if and only if the vehicle has been sent to a depot.
+	 * @return True if the current order was changed.
 	 */
 	static bool SendVehicleToDepot(VehicleID vehicle_id);
 
diff --git a/src/ai/api/ai_waypoint.hpp b/src/ai/api/ai_waypoint.hpp
index 69eacb10e6..9e1bec9110 100644
--- a/src/ai/api/ai_waypoint.hpp
+++ b/src/ai/api/ai_waypoint.hpp
@@ -16,7 +16,7 @@ public:
 	static const char *GetClassName() { return "AIWaypoint"; }
 
 	enum SpecialWaypointIDs {
-		WAYPOINT_INVALID = -1, //!< An invalid WaypointID.
+		WAYPOINT_INVALID = 0xFFFF, //!< An invalid WaypointID.
 	};
 
 	/**