Continuity mistake: When Michael is talking about Seth's girlfriend, Joey has a board of cheese and grapes out. When the shot changes, the grapes have disappeared off the board. (00:05:35)
Other mistake: In season one when Alex got divorced, Joey and Gina talked about how Gina got divorced from Michael's father while she was still in high school. In season two, we learn that Jimmy is Michael's father. Joey didn't even know that they were together, he certainly would have known if they were married.
Continuity mistake: When Joey and Michael are talking to Roger, and everyone is drinking shots, when Joey and Michael put their glasses back down, we see that they're both on the tray, yet in a later shot, we see one of them is not on the tray any more, but further along the table. (00:16:35)
Continuity mistake: Just after the opening credits, when Joey runs out to see Jake, Jake has one hand out in one shot and then puts the basketball in both hands. When the shot changes, his hand is out again and then he puts the basketball in both hands again. (00:04:15)
Joey and the Book Club - S1-E4
Continuity mistake: When Joey is trying to read the book for book club, we see he kneels down on both knees to look at a snail, then when the shot changes, we can see that he is only kneeling down on one knee. (00:12:25)
Continuity mistake: When Michael is happy about Gina dating, we see Joey celebrate as well, he throws his hands in the air and when they come back down, they are apart, then when the shot changes, they are interlocked. Then when Joey points at Michael, he does it with his left hand and when the shot changes it is with his right hand. (00:12:05)
Continuity mistake: Episode 1-19 Joey and the Fancy Sister. When they are looking at the engagement ring under the black light, the ring goes from Joey's hand to Gina's instantly between shots.
Plot hole: In the episode where Joey tells Jimmy that Michael is his son and they cut of some of his hair to do a DNA test, Gina tells Michael that he is missing some hair on the back of his head. In the next shot the angle changes, we can now see the back of Michael's head, and he's not missing any hair.
Continuity mistake: When Michael, Joey and Gina are talking just after the opening credits, we can see that the writing on Michael's laptop changes between shots. (00:02:20)
Joey and the Big Audition - S1-E10
Continuity mistake: When Joey goes into his audition, we can see that the bag is no longer on the couch, if you look through the gap in the door. (00:17:50)
Joey and the Dream Girl (1) - S1-E8
Continuity mistake: When Michael tries out baseball, we see him holding the baseball bat, then when the shot changes, after Joey asks him for another quarter he is no longer holding it. (00:15:45)
Joey and the Big Audition - S1-E10
Continuity mistake: In the scene were Michael is running lines with Joey, the position of Michael's book keeps changing position on the foot stool in between shots. (00:14:25)
Joey and the Perfect Storm - S1-E5
Continuity mistake: When Joey goes to visit the sick actor in bed, the tissues in the actor's hands and on the sheets disappear between shots.
Continuity mistake: When Joey goes to see his agent, we can see the paper pad and the pen move in between shots. (00:07:55)
Revealing mistake: When Joey is climbing the wall, you can see that the piece of wall he breaks has a break line in it.
Joey and the Big Audition - S1-E10
Continuity mistake: When Joey is going to his Deep Powder audition, when he meets Katie, throughout the entire scene, the piece of paper changes positions in her hand, in between shots. (00:09:00)
Joey and the Perfect Storm - S1-E5
Continuity mistake: During the end credits, the amount of milk in Michael's glass keeps changing. (00:20:35)
Joey and the Plot Twist - S1-E12
Continuity mistake: When Joey asks Alex to give him a second we see her put the script in her right hand, then when the shot changes, we see it's under her left arm. (00:16:45)