In the church scene when the meeting is broken up by the thugs outside there is a long shot with the characters trying to decide which way to run and you can see a boom mic bouncing around for a few seconds at the top of the screen.
When Father Barry (Karl Malden) gets hit in the head with a beer can, he gets a cut on his forehead, which bleeds visibly in the scene. In subsequent scenes, there is no sign of the cut or of a bandage to show that he had been hurt.
In the last scene, as Brando makes his way to the warehouse, after being beaten up by Cobb and the goons, the chalk writing on the sign changes from "8:00 am (plus two lines), to: "5 full crew & 5 Extras"
After Terry is beaten senseless and Fr. Barry and Edie go to pick him up, Terry is clearly wearing ankle high work boots. However when he is stumbling towards the loading dock the camera cuts to his feet for a few seconds and now he is wearing low cut work shoes.
During the climactic fight between Terry and Johnny, Johnny loses his scarf at one point as he and Terry scuffle. There are a couple of shots after that showing the longshoremen and Johnny's henchmen watching the fight, but when we cut back to Terry and Johnny, Johnny's wearing his scarf again. Terry then hits him and we get a closeup shot of Johnny falling against the wall and calling his henchmen for help, and in this shot the scarf is missing again.
After John Friendly is shoved in the river, when he reappears exhorting the dockworkers to obey him and not to follow Terry Malloy and Father Barry, Lee J. Cobb's clothes are dry and he is well groomed again in spite of the brawl & the dunking in river water.
At around 1h 4 mins when the waterfornt crew are in the Longshoreman's Local 374 hut and Johnny Friendly is telling Charlie to sort out Terry, Mac is seen reading and his seating position changes between shots.
In the beginning of the movie in the first bar scene after Terry has set-up Joey Doyle, when 'Skins', the man from 'Greenpoint', is asked by Johnny Friendly if he "handled the sheet metal", Skins says, "yes, it was easy, here's 45 Bills" (meaning $4,500.). Friendly gives the money to Terry's brother, Charlie the Gent', to count. After he does Charlie erroneously tell Friendly the total is $2673.00, i.e., the amount 'Big Mac' says is the total of Friendly's cut from the day's shape-up of the 813 Union members that worked that day, instead of $4500.
As the scene in which Terry coaxes Edie into walking home with him dissolves, Eva Marie Saint breaks character by abruptly stopping and turning around to head back towards the crew area near the camera.
The prosecutor at the hearings is shown on TV facing Terry in the witness stand, but in the hearing room there is no television camera located behind the stand, where it would have to have been for the angle shown in the TV picture to be possible.