Factual error: Philadelphia Athletics players are wearing green. They didn't wear green until 1963. They wore blue prior to that, very similar to Dodger blue.
Factual error: Joe Jackson batted left-handed in real life, not right-handed as Ray Liotta portrayed. He also threw right-handed and not left-handed like it shows when Kevin Costner is hitting him fly balls to left field.
Visible crew/equipment: On some shots which look back at Ray when he's driving his pickup, it can be clearly seen at the bottom of the picture that the front wheels of the pickup are sitting on a trailer, which is itself being towed by the camera vehicle.
Continuity mistake: When Annie and Ray are laying in the newly completed ball field, and Annie is drinking a glass of wine, it is sunset. The sun has gone down and the sky is just the faintest of pink on the horizon, the rest of the sky is a strong blue tone. Yet, when the camera cuts to a long shot, same angle of Ray and Annie, the horizon is now a brilliant red-orange taking up nearly a third of the sky. (00:16:20)
Continuity mistake: In the scene where Ray has a catch with his father, Ray's brother-in-law's Jeep can be seen parked near the light pole along the third base line. In the next shot, the Jeep isn't there. When the shot again changes and the camera pans back, the Jeep is back by the pole.
Continuity mistake: When Ray and Annie are at the PTA meeting, it is night when they go inside, but when they come out after Annie gets into the argument with the other woman, it is day (there is sunlight coming through the windows).
Continuity mistake: While Ray and Terence Mann are at the Red Sox game, they receive a message on the scoreboard - but the time and score don't reflect what Ray has written on the scorecard on his lap. Before Ray hears the voice it is 8:41, but right after it is 10:30.
Continuity mistake: When Ray and Joe Jackson first take batting practice in the field there are five bats against the backstop. To their left is the bag with the remaining bats, the bag at first has the appearance that there is the strong outline of a bat or a bat behind the bag, yet when Joe goes to retrieve another bat the bag is loose and in an entirely different shape. (00:22:00)
Continuity mistake: The grocery bag in back of the truck shows a red and white milk carton sticking out of bag. In a following shot the grocery bag no longer has the milk carton sticking out of the top. Then upon entering the house, the same grocery bag now has a blue and white milk carton sticking out, plus other items not seen before. (00:41:15 - 00:42:35)
Continuity mistake: In the scene Costner is chopping up his corn crop with a flail hopper, the PTO that drives the machine is not rotating.
Continuity mistake: At the end of the film, when Ray is saying "Good-night" to John, the sun has set and the sky is cloudless and pink just along the horizon. In the next shot, when Ray asks, "Dad" for "a catch" the sky is much brighter and there are many clouds reflecting the now setting sun. (01:37:40)
Continuity mistake: When Ray first comes down for breakfast and "Harvey" is on TV, the Wonder Bread is next to the TV. But in the next shot the bread is farther to the right with the milk now between the TV and the bread, although Annie was not in the vicinity to have moved them. (00:07:40)
Character mistake: Chick Gandil mispronounces Eddie Cicotte's name, calling him "Si-coty" instead of "See-cot."
Factual error: When Ray is walking around the Chisholm Minn, he wipes the dirt off a license plate to reveal a sticker showing the year '72. While Minnesota began using stickers in 1972, they only started putting them in the lower right starting in 1975, with all plates before 1975 containing an embossed year in the lower right.
Factual error: When Ray is in the feed store, he picks up a bag of seeds from the counter and casually walks out. These bags of seeds weigh 50 pounds, so to lift it in the manner he did would require a great deal of strength.
Revealing mistake: At Fenway, when Ray sees the scoreboard cycling through images, watch the crowd below the scoreboard. They jump as if the scene cuts or is looped.
Revealing mistake: The time on the scoreboard clock when Ray hears the "go the distance" message changes from 10:30 to 10:32 in a matter of seconds.
Continuity mistake: The sun changes constantly during the "people will come" sequence. Particularly, long shots of Shoeless Joe and Ray. The sun is overhead and deeper in the west in the space of seconds.
Visible crew/equipment: Ray and Annie are talking about going to Boston and the camera is tracking through their home. The camera is reflected in a picture hanging on a wall in the kitchen as the shot passes it.
Continuity mistake: During Terrance Mann's "people will come" speech, the sun moves around quite a bit. The scenes of the baseball players have long shadows. The scene with Ray has the sun overhead. When Karen falls it is late afternoon again. When Doc leaves it is early evening. From Shoeless Joe's angle it is late morning.
Answer: It was actually his own voice (Kevin Costner) that sent him on the journey. At the end of the movie there's even the part where Ray is recalling the voices he heard and turned to Shoeless Joe Jackson and says, "It was you". At which point Joe Jackson turns around and says, "No Ray. It was you".