The development of Call of Duty: Finest Hour was hindered by mismanagement, technical problems, and three legal disputes. Developer Spark Unlimited's founders had previously worked on the Medal of Honor series and recruited a number of developers who worked on Medal of Honor: Frontline while they were still earning paychecks from Electronic Arts. EA sued the company for this, and also accused them of copying proprietary development resources. The two parties settled, forcing Activision to pay $850,000 in legal bills before development even began.

Although Activision advised against it, Spark Unlimited chose to build the game using the RenderWare engine, which did not work well with their custom object database and caused the game to frequently slow down and crash, while inadequate development tools made debugging and fixing problems more challenging. There was also a major difference between their approaches to game development. Spark Unlimited preferred to concentrate on building the levels first and leave technical polish until later, whereas Activision wanted the core game to be polished much earlier in production and would potentially ask for features not originally negotiated in their contract, in particular the game's multiplayer mode. This caused Spark Unlimited to repeatedly miss development milestones and go overbudget, forcing Activision to bring in a team of its own engineers and outsource work to contract developers, including work on the Xbox and Nintendo GameCube ports. A second lawsuit occurred when Spark Unlimited's chief technical officer Adrian Jones resigned during development in 2004.

Despite the game's financial success, Activision had lost confidence in Spark Unlimited's management and their pitch for a sequel, and ended its contract with them. This led to a third legal dispute in 2005 when both companies sued each other, with Spark Unlimited accusing Activision of unpaid royalties and Activision accusing Spark Unlimited of misleading them. This case was also settled out of court.