As Phil walks off the stage after performing the piano number, two background actors behind him are visibly 'fake clapping', but there is no clapping sound to accompany it. Whilst this is a technique used on set when recording dialogue, so the background actors' clapping does not get recorded by the actors' microphone, for some reason the sound editor missed this or decided not to dub it with 2 people clapping, giving this strange looking result.
In the last part of the movie, Phil is seen playing the piano on stage at the party. As he finishes up song before going and talking to Rita, the piano in the soundtrack is playing a glissando (running a finger rapidly down the keyboard) while Phil is still playing as he was before. Finally, at the last run, Phil's hands match the sound.
In the Bavarian restaurant, a poster appears on the wall reads "Alles Gute Zum Erdhörnchentag". This is supposed to mean "Happy Groundhog Day", but is, however, a mistranslation because "Erdhörnchen" means "Gopher". The poster should have read "Alles Gute Zum Murmeltiertag".
At the beginning of the scene where Phil and Rita talk in the Bavarian restaurant, a waitress crosses carrying 4 large steins of beer. She sets them on the table behind Phil and Rita. Watch as she walks away from the table. She touches the shoulder of the older gentleman seated at that table and leaves foam on the top of his jacket sleeve.
On the first day Phil wakes in the hotel he looks out of the window and sees certain cars moving and turning. The next day he looks out of the window again and sees exactly the same cars etc as though it is exactly the same time, but the time is different which we know because the radio show that we can hear is at a different point.
During the final party scene, the engaged couple approaches Phil, and he introduces them as the newly-married "Debbie and Fred Kleiser." However, earlier in the movie in the diner, the indecisive bride-to-be is already introduced as "Debbie Kleiser," prior to the wedding having occurred, presumably prior to her having taken her husband's last name.
During the police chase scene on the railroad tracks, there is a shot where the train's headlights illuminates the tracks in front of the Phil's car. In that shot we can see that there is no break in the tracks. In the next shot they veer off the tracks, via a road without any rail crossings, and escape.
As Phil is walking toward the town plaza and he rounds the corner and passes by the old beggar, a number of shops can be seen over his shoulder to the right of the screen. This scene is repeated many times in the movie, and sometimes there are flags flying over the shops, while other times there are none.
At the beginning of the movie, while the white van is going from Pittsburgh to Punxsutawney, the WPBH signs stuck on the van's sides move from near the back of the van to near the front (see the 4 semicircular holes above each sign).
On February 3rd, when Phil and Rita are leaving the place Phil has been staying, the shots of the gate in the fence show the gate closed in the shots from near the building, but show the gate open in the shots from the street.
During the police chase when Phil is being chased down the railroad tracks, the police car has a rotating light bar. In close up shots the police lights flashing behind the vehicle are clearly strobe lights.
When the police are chasing Phil in the Cadillac convertible, he wrecks into a row of cars, the first one being a 1983 AMC Eagle wagon. In the next scene, the Cadillac is crashed against a small Chevy, and the Eagle is on the other side of the Chevy.
Since every day takes place on the same day there should be the same amount of snow every night. However, there are clearly some nights where there is a lot of snow and others where there is no snow at all.
When Needle-nose Ned spots Phil and says his name: Phil??!! The "first" Feb. 2nd, Ned's voice hits a very high note, but the following Feb. 2nds his voice doesn't reach that high note. One point where the original soundtrack should have been used.
When Phil is ready to leave the B&B on the first repeat day his scarf is outside of his unbuttoned jacket. Yet once he turns around and exits through the front door his jacket is buttoned and the scarf is tucked inside.
At the beginning of the movie when Phil is giving the weather report he claims that if he had a choice of where he could be, he would choose Elko NV, because that was the location of the nations high of 79. On February 01, the day before Groundhog's Day, Elko would be very cold. It would not be a place that would have the nations highest temperature in February. The highest temperature in Elko NV in the last 75 years was 21C (about 69F) and that was late February 1905.
In the first scene where the bed & breakfast is shown, it is 5:59AM and it's already light outside. In Punxsutawney, PA the nautical twilight is at 5:51 AM on 2 February and in Woodstock, IL where the movie is filmed, the nautical twilight is not until 6:02AM. It is not possible that it would be as bright outside as depicted in the film.
When Phil is reading poetry to Rita back at his room, Rita dozes off. When she awakens, Phil says, "I think the last thing you heard was, 'Only God can make a tree'." This is a partial quote of the last line of Joyce Kilmer's famous poem "Trees". Unfortunately, either Rita must have been dreaming it, or Phil must have been quoting it from memory, as Kilmer's poem is not included in the book Phil is reading from, namely: "Poems for Every Mood", compiled and edited by Harriet Monroe in 1933.
Phil says, "Well maybe the *real* God uses tricks, you know? Maybe he's not omnipotent. He's just been around so long he knows everything." Knowing everything is not omnipotence, it's omniscience. The actor might have read the line wrong.
We never see Phil try to leave first thing in the morning before the highway gets blocked, but that doesn't mean he didn't try, fail, and give up; there could be many things he tried that we don't see before he finally decided to settle down.
On Phil's first repeat day he says the radio DJs are using yesterday's tape, as evidence that he knew they would say "chapped lips". But once they mention that today is Feb 2nd, Phil gets suspicious, yet he shouldn't because he believes it's a recorded tape that's playing.
Phil's morning routine varies from Groundhog Day to Groundhog Day, e.g. the amount of time he spends in the breakfast room or talking to other guests or the proprietor, but he meets Ned at exactly the same point of time and location every time.
While on his death binge, the pickup truck Bill and Phil uses to drive over the cliff clearly has no engine or drive-train components. The underneath shot is even depicted in slow-motion, and one can see clear through to the radiator.
Phil's room in the Cherry Street bed and breakfast is on the top floor overlooking the street. The sizes and number of windows inside his room do not match any combination of those from the exterior shots, which is due to the fact that the interior shots were not filmed on location.
On the third morning, Phil rushes out of the hotel without interacting with the chubby guest and the female hotel proprietor, which should put him ahead of schedule. However, as he exits the hotel, the piano teacher has already crossed the street, and his encounters in town (e.g., Ned) occur on schedule.
In the diner, when he's proving that he knows about everyone, Phil introduces Rita to "Debby Keisler and her fiancée Fred." At the Groundhog Dance near the end of the film Phil introduces the pair, now married, as "Debby and Fred Keisler." Either they already had the same last name, Fred took Debby's last name, or somebody screwed up.